THE BIOLOGICAL BASfS OP MENSTRUATION. 
BY 
J. C. WEBSTER, M.D., F.R.S.E. 
(Reprinted from the Montreal Medical 1897.) THE BIOLOGICAL BASIS OF MENSTRUATION.1 
BY 
J. C. Webster, M.D., (Edin.), F.R.C.P.E., F.R.S.E. 
At the present time there is universal ignorance as regards the 
causation of menstruation, its meaning as a sexual character, and the 
method by which it has become established among the higher mam- 
malians. 
The following views have been advanced to explain the meaning of 
the process : 
1. Relation to Ovulation.—lor a long time it has been believed 
that ovulation and menstruation are so closely related that they occur 
at or about the same time, the former being the cause of the latter. 
Of those who hold this view, some think that the blood-discharge 
results from a general pelvic congestion, supposed to be present during 
the ripening and escape of the ovum. Thus, Mathews Duncan often 
compared the menstrual flow to the red flag outside the door of an 
auction-room, which indicates that something is taking place inside. 
Others regard menstruation as a process induced by ovulation 
necessary to the preparation and development of the ovum, in case it 
should be fertilized. 
A careful examination of the evidence on which these statements 
are founded reveals their untrustworthiness. It is, indeed, a wonder 
that they have so long been believed. 
The following facts relating to maturation and escape of the ovum 
are now definitely ascertained. These processes are usually in opera- 
tion some time prior to the development of the phenomena of puberty 
before menstruation appears ; sometimes they occur in childhood and 
1 Read before the Montreal Medico-Chirurgieal Society, Jany. 12th, 1897, and 
before the New York Academy of Medicine. 2 
in foetal life. There is no proof at all that pelvic congestion takes 
place, either coincident with or secondary to these processes, at any 
time in a woman’s life. 
Ovulation may also occur without menstruation in the dodging- 
period of puberty and of the menopause; for several years after the 
menopause as Hegar has pointed out; during lactation ; in certain 
diseased conditions, e.g., anaemia, phthisis, lead-poisoning. Pregnancy 
may take place at any of these times. DeSinety describes an inter- 
esting case which he examined, of a woman, 38 years of age, who had 
never menstruated. In the ovaries there was the normal condition of 
Graafian follicles, and corpora lutea indicating that ovulation had 
taken place. The body of the uterus was undeveloped. 
Then, in abdominal and post-mortem sections made at all times 
between menstrual periods, Graafian follicles may be found on the 
point of rupture or recently ruptured ; and in examinations made 
during menstruation, no sign of ovulation may be visible. 
(In this connection it is interesting to note that Heape examined 
the pelves of forty-two monkeys (Semnopithecus entellus) during 
their menstrual periods and found evidences of ovulation being in 
progress in only two cases.) 
It is a common observation that extensive disease of both ovaries, 
e.g., cystoma, suppuration, malignant growth, may not effect the men- 
strual function to any appreciable extent in many cases. 
These various facts are sufficient, it seems to me, to overthrow the 
view that menstruation is a necessary accompaniment or sequel of 
ovulation. 
Yet it can scarcely be denied that there is some relationship between 
the processes. 
Removal of the ovaries is followed by cessation of menstruation 
though in a certain number of cases this does not happen. As an 
interesting instance of this, may be mentioned Lawson Tait’s patient 
from whom both ovaries and tubes along with a part of the uterus 
were removed, menstruation still continuing. 
These exceptions have been carefully considered by several authori- 
ties, lately by Rland Sutton. He states that the reported cases have 
been mostly those in which chronic inflammation in and around the 
appendages has been present, or those in which operation has been 
performed for myoma uteri. His explanation of the persistent men- 
struation is that either small bits of the ovary have been left behind? 
or that in the cases of myoma a submucous tumour may exist leading 
to haemorrhages. Many cases have undoubtedly been recorded in 3 
which after removal of the ovaries for fibroid, menstruation has con- 
tinued. 
The long held view of supernumerary ovaries is discarded by Bland 
Sutton. He thinks that these so-called structures are merely small 
bits separated from the main mass of the ovary by deep fissures. 
In several of these cases of unchecked menstruation, second opera- 
tions have been performed by which small bits of ovary left from the 
first operation have been removed, being followed by a complete 
cessation. 
2. Relation to the Fallopian Tubes.—According to Lawson Tait, 
removal of the tubes, the ovaries being left in situ, is followed in 95°/Q 
of cases by cessation of menstruation. This remarkable statement 
has been little noticed. If it can be established by extended observa- 
tions, it proves that there is some close relationship between the tubes 
and the menstrual process. 
3. Relation to a Special Nervous Mechanism.—Johnstone has 
advanced the view, supported by Lawson Tait and others, that the 
menstrual act is a special function related to a distinct nervous 
mechanism. They think that possibly a special nerve trunk running 
in the upper part of the broad ligament may convey the regulating 
currents. Johnstone suggests that when the ovaries or tubes are 
removed, menstruation is checked because this nerve is ligatured or 
divided. In the cases in which removal of the appendages is not 
followed by cessation of the flow, he thinks that the nerve may have 
escaped division or ligature, owing possibly to its being placed low in 
the broad ligament. 
While undoubtedly believing in this special nervous mechanism of 
menstruation it seems to me that possibly the nerve tract is not so 
limited as Johnstone suggests. The plexiforin nature of the nerves 
about the uterus is so complex that it is presumable that the impulses 
affecting the mucosa of the uterine body travel by many routes in the 
broad ligaments. 
4. Relation of Menstruation to Conception. —By some it is believed 
that menstruation is a process for preparing the uterine mucosa for 
the engrafting of the fertilized ovum, that it is in fact, an essential 
feature. This idea was promulgated when it was thought that the 
ovum required a connective tissue free from covering epithelium to 
become engrafted on. I have repeatedly urged its improbability on 
the following grounds : 
a. In all mammalians below homo, so far as is known, the ovum 
grows in relation to the epithelium-covered uterine mucosa and does 
not require a connective-tissue surface. The uterine epithelium is 4 
undoubtedly non-essential, but it is destroyed by degenerative pro- 
cesses and by the trophoblastic action of the outermost layer of the 
foetal epiblast. As far as our observations go in human development 
the same processes occur there. 
b. Pregnancy may occur in a girl before the onset of menstruation, at 
a time therefore, when the mucosa cannot be denuded by that process. 
c. It may occur during the lactation period, long after the uterine 
mucosa has been restored, and at a period in which menstruation is in 
abeyance. 
d. It may take place in one of the periods of amenorrhoea during 
the progress of the menopause. 
e. It may occur in periods of amenorrhoea due to diseases e.g., 
anaemia, phthisis. 
/. Clinical experience of cases of pregnancy following a single 
coitus proves that development of the ovum may begin at any time, 
not necessarily immediately after menstruation. (It must be stated 
that this evidence is of doubtful significance, owing to the uncertainty 
in our knowledge as to the time it takes the ovum to pass from the 
ovary down through the genital tract and as to how long the sperma- 
tozoa may live in the tract.) 
g. Pregnancy may occur in the rudimentary horn of a malformed 
uterus, menstruation never having taken place in that horn. 
(Whereas, as P. Mueller points out, there is no record of pregnancy 
having ever occurred in the horn of a bicornuate uterus which is 
atresic in its lower part; menstruation goes on in it, as we know, the 
blood accumulating above the atresia). 
h. It may occur years after menstruation has ceased at the supposed 
menopause. An interesting example is Renaudin’s case in which a 
woman of sixty-two was delivered though she had not menstruated 
for over ten years. 
i. In male pseudo-hermaphrodites, possessing testes but no ovaries, 
the vagina, uterus and tubes may be present and menstruation may 
go on regularly or irregularly. 
Another view is to the effect that, along with the maturation of the 
ovum, the endometrium swells as the first stage in the formation of a 
decidua which will receive the ovum if it be fertilized. If fertiliza- 
tion does not occur, breaking down of the superficial portion, the so- 
called “ menstrual decidua ” occurs, and the menstrual discharge takes 
place ; in this way menstruation may be regarded as the expression of 
the failure of a process meant to be initial to pregnancy For, if fer- 
tilization occurs, it is thought that the swollep mucosa advances to 
form the decidua of pregnancy. 5 
This view, it is evident, is based upon a fallacious assumption, and 
my objection to the last mentioned theory may be quoted to refute it. 
There is no proof whatever that changes in the mucosa accompany 
maturation of the ovum, and the best evidence we possess regarding 
the alteration in the uterine mucosa during menstruation, viz., the 
observations of Johnstone, Bland Sutton, Heape, Minot and Mendl 
goes to show that practically only blood and small portions of the 
lining epithelium escape. There is normally no exfoliation of a layer 
worthy the name “ menstrual decidua.” 
I think this term is a bad one ; it is to be clearly understood that 
no change occurs in the connective tissue elements of the mucosa dur- 
ing menstruation, viz., enlargement of cells. This change only occurs 
in connection with the influence of a fertilized ovum. 
Lowenthal has advanced still another explanation. He believes 
that menstrual bleeding is neither a physiological function nor an 
accompaniment of one, but that it is due to innumerable repetitions 
of an unnatural state of things, viz., the non-fertilization and death 
of the ovum. He says that the swelling of the uterine mucosa is the 
result of the embedding in it of the last ovum discharged from the 
ovary. If this ovum be fertilized the swelling mucosa goes on to 
form the decidua of pregnancy ; if no fertilization takes place, the 
ovum dies, and as a result of this death a breaking down occurs in 
the mucosa. He, therefore, regards the menstrual flow as having all 
the characteristics and effects of other bodily haemorrhages. 
Lowenthal’s view is a piece of speculation without any factual 
basis. No one knows anything about the unfortunate ova which do 
not fulfil their highest destiny. It is a sympathetic imagination 
which makes them cling in their downward course to the walls of a 
repellant uterus, forcing changes upon that organ, in the fond hope 
that a wandering spermatozoa may cleave to it in consummative union. 
Fanciful also the picture of death following bitter disappointment, 
the coincident decay of the dead ovum’s resting place and the final 
bearing away in a blood-red funeral stream of the fragments of a once 
active individuality. 
Johnstone believes that the simplest definition of menstruation is a 
periodic wasting away of the corpuscles that are too old to undergo 
the changes which must occur in connection with the attachment and 
development of the fertilized ovum. He does not regard the endo- 
metrium above the internal os as mucous membrane, but as belonging 
to adenoid tissue. 
Menstruation is for it what the lymph stream is to the lymph- 
gland or the blood stream to the spleen. The development of the 6 
corpuscular elements, lie thinks, takes place in the endometrium, as in 
the blood-glands, spleen, thyroid, etc. 
The existence of menstruation in the human female and its absence 
in the mammalian orders below the Primates, he explains by postural 
differences, and by difference in the structure of the endometrium. 
From his studies he is of the opinion “ that nature has supplied the 
endometrium with an abundant lymph stream, which in the unimpreg- 
nated state washes away the ripe material to the general circulation 
exactly as it does any other lymph corpuscle. But in woman, where, 
on account of its erect position, the uterus has to depend on the tenacity 
of its own fibres for the preservation of its shape, no such thing as 
loose tissue of a lymphatic network can be depended upon. So, to 
preserve the integrity of the uterine wall, the emulgent stream is 
poured into the cavity of the body, and got rid of through the vagina.” 
5. Relation to Body Metabolism.—Geddes and Thomson in their 
“ Evolution of Sex ” have advanced the theory that the menstrual 
process is related to the balancing of anabolism and katabolism in the 
female organism. 
After puberty a surplus is produced in the system because the 
anabolic preponderates over the katabolic. When pregnancy occurs 
this excess is spent in the nutrition of the ovum during its parasitic 
intra-uterine life and during lactation. When these methods of using 
the anabolic surplus are wanting, menstrual losses occur in order that 
it may be got rid of. 
Biological Considerations.—Scarcely any attention has been given 
to the consideration of menstruation in its biological aspects. 
The speculation of the distinguished biologists, Geddes and Thomson, 
is one of the most suggestive which has yet been advanced, and it is 
worthy of an elaborate study. 
The careful investigations of many forms of plant and animal life 
by zoologists and botanists, have enabled the biologist to establish a 
distinction between “ maleness ” and “ femaleness ” not only in terms 
of morphological characters but of psychological and physiological 
reactions. It is only recently, however, that sex differences have been 
investigated on these more subtle and difficult bases of inquiry. Too 
long have reproduction and sex been considered by themselves as if 
they were something to be disassociated from the general physiology 
of the organism. 
The most important sex-distinction which has been established is 
that which has to do with the general metabolism, or protoplasmic 
chemistry of the body. Every living cell and every organism is con- 
tinually representing two forms of metabolism : one, the anabolic, by which nutrition is taken in, waste repaired, energy stored, structure 
improved or altered ; the other, the kata'bolic, by which potential is 
changed into kinetic energy and movement or activity manifested, 
structural alterations induced and waste created. 
Throughout the animal kingdom the distinctive and predominant 
characteristics of the male sex is katabolism and of the females, ana- 
bolism. 
Generally speaking, the males show activity, continual expenditure 
of energy, disruptive metabolism ; the females, passivity, quiescence, 
constructive metabolism. 
The same distinction is also found in the plant world. The lines of 
inquiry on which this generalization has been made are the following : 
1. A study of sexual characteristics in the fully developed state 
and in the history of the individual. 
2. An investigation into the condition of the lowest forms of animal 
and plant life, where sex has its beginning. 
3. Observation of normal and pathological changes in the reproduc- 
tive apparatus. 
4. Experimental inquiry into the nature of the factors which deter- 
mine sex. 
Details regarding these lines of research are beyond the limits of 
this paper, yet some reference must be made to them. 
As regards the differences found in the adult forms in the inverte- 
brata and among fishes, it may be stated that in general the body 
temperature is lower in the female. (This is so in many plants). 
Their longevity is greater. They are in general larger and more 
sluggish in habits. The males expend energy more freely, thus pre- 
venting storage-accumulation and increase in size. Among birds 
and mammals, while the general metabolic differences exist the males 
are usually larger than the females owing to special factors which 
have come into operation and which do not exist in the lower orders 
of life. Darwin and Geddes have explained these. They show that 
the differences in size in the higher forms are mainly in bones and 
muscles. This is explained partly by the extra stress and strain 
thrown on the males while the females are in a state of pregnancy 
and caring for the young ; partly by the strengthening effect of fights 
between the males, the strongest tending by natural selection to per- 
petuate their kind ; partly by the effects on the female constitution 
of the excessive reproductive demands found among the higher 
animals. 
The distinction between the sexes is universally marked in the 
spermatozoon and ovum, the former being small, active, energising 8 
katabolic; the latter large, passive, highly nourished, anabolic. 
While the metabolic differences between male and female have been 
mainly studied in plants and the lower animals, some work has also 
been done in the human subject, though here the difficulties are 
greater owing to the greater complexity of the organism. 
Blood—The red corpuscles are more numerous in the male, and the 
percentage of haemoglobin greater than in women. The specific 
gravity is the same until puberty. Afterwards it is higher in men 
than in women during the sexual life. In old age it is usually higher 
in women. 
It is thns evident that the menstrual life is associated with a fall 
in the specific gravity of the blood. 
Pulse rate.—The pulse rate is slower in men than women. This 
holds good for nearly all animals. 
Respiration.—Men produce more carbonic acid than women as 
estimated by the breath. After puberty the amount is nearly double 
that produced by women. It increases in the latter during pregnancy 
and after the stoppage of menstruation. 
Excretion..—The urine of women is usually lighter in colour than 
that of men, and its specific gravity lower. The amount of urinary 
solids is both absolutely and relatively less than in the case of men, 
especially during the reproductive era of her life. 
It is highly probable that those features which we call secondary 
sexual characters, e.g., richer pigmentation, excess of hairs and feathers, 
activity of scent glands, etc., which are found in the males are but the 
multiform expressions of the katabolic predominence in the male 
organism. And it is important to note that in the great run of cases 
these characters are fully developed as maturity is established. In 
early life there is practically no physiological distinction between the 
sexes. The establishment of the reproductive functions is associated 
with the development of sexual features, which, as Darwin has 
pointed out, modify the males to a much greater extent than the 
females, throughout almost the entire animal kingdom. “ Generally,” 
he states, “ the female retains a closer resemblance to the young of 
her own species than to other adult members of the same group.’ 
Experimental evidence regarding the influence of various conditions 
in the production of sex, points also strongly towards the conclusion 
that “ in the determination of sex, influences inducing katabolism 
tend to result in the production of males, as those favouring anabolism 
similarly increase the probability of females (Geddes and Thomson). 
Poor or abnormal food, deficient light, moisture, exercise, excessive 
lactation and other conditions tending to diminish the repair-supply 9 
or to cause a surplus of waste—the katabolic habit, tend, in experi- 
ments made on lower animals, to the production of males. Such tests 
strengthen the view that the male is the index of a preponderating 
katabolisin, and the female of an equally marked anabolism. 
Now, throughout the greater part of the animal kingdom, this 
anabolic predominance in the female affords the means of counteract- 
ing the katabolic influence of the part she has to play in reproduction. 
During the sexual life of females among most of the Primates, the 
anabolic habit does not find sufficient employment in supplying this 
destructive influence. An overplus exhibits itself in the production 
of milk during the early period of the child’s life, and, after lactation, 
in a discharge of blood from the uterus. 
Cases of menstruation during lactation might by this theory be 
easily explained. The production of milk does not use up the ana- 
bolic surplus, which, therefore, becomes disposed of through the sexual 
menstrual outlet. 
In all mammalians below the primates the balance is regulated 
without the occurrence of any loss through menstruation ; reproduction, 
lactation, the care of the offspring and their moving habits apparently 
making such demands upon the maternal anabolism that no surplus 
corresponding to the menstrual blood of the human female is pro- 
duced by the system. 
(In the vegetable kingdom, also, it is interesting to note, “ the dis- 
tinctly anabolic overflow of nectar ceases at fertilization, and the 
surplus of continual preponderant anabolism is drafted into the grow- 
ing seed or fruit.”—Geddes and Thomson.) 
One of the most striking characteristics of menstruation, as observed 
in the human female, is its variability in type, and in the quantity 
and duration of the discharge. 
One need not specify these in detail. I wish in particular to direct 
attention to the great range of variation in the time of its appearance 
in relation to the development of those other phenomena which we 
call the “ sexual characteristics.” 
In the majority of cases these features e. g., activity in ovulation, 
menstruation, hair-development, growth of breasts, etc., become estab- 
lished at a definite period, known as puberty, which, as we know, 
varies according to climate, race, environment and other conditions. 
But of far greater importance are the variations which prove that 
there may be no concurrent incidence in the determination of the 
phenomena in the individual. They are as follows : 
1. Menstruation may begin very early in life, even within the first 
year, without the development of any of the other outward signs of 10 
puberty. These become marked, at varying periods in different cases, 
and in different orders. Generally, they appear together after a 
number of years, but sometimes the breast changes precede the others, 
sometimes the growth of hair, sometimes the changes in bodily 
contour. 
2. In other cases, the development of menstruation at a very early 
period may be associated with one or more of the other secondary 
sexual characteristics. Thus the breasts may be well-marked, or the 
external genitals well-developed, or the voice altered. The other 
features appear in later years. 
d. In other cases some of the secondary sexual characteristics other 
than menstruation may be developed in very early life, this function 
becoming established sooner or later afterwards. Thus the breasts 
may become well-marked, menstruation following after months or 
years. In a casp recorded by Bouchut, in which the breasts were 
well-formed at birth, menstruation began at the age of 22 months* 
and the rest of the sexual features became marked in the succeeding 
2 years, so that at the age of 4 years the child had all the characters 
of a fully developed girl. 
Sometimes the breasts and external genitals may develop early 
together. Sometimes the latter alone may be very early marked, 
being followed sooner or later afterwards by menstruation and the 
other phenomena. 
Sometimes the breasts develop early along with axillary and pubic 
hairs, being followed after months or years by menstruation. 
Sometimes the body-contour may resemble the adult form, the hair 
and external genitals being well devejoped, at a very early period ; 
the appearance of menstruation and the growth of the breasts being 
delayed for months or years. 
4. As regards the condition of the internal genitals, only a few 
opportunities have presented themselves of observing them in the 
above-cited cases, so that it is impossible to know in how many 
ovulation was in progress or the uterus well-developed. It is, how- 
ever, clearly established that in some of these precocious cases ovulation 
is in progress and the uterus with adult features There can be no 
doubt, therefore, that puberty may be completely developed in the 
first years of life as regards the physical changes. As is to be ex- 
pected the psychical alterations are wanting. 
5. Finally, the cases must be alluded to, in which during infancy 
and child life, ovulation has been noted, though none of the other 
signs of puberty have been present. Tt has been found in progress 
even before birth. In the great majority of cases of normal develop- ment of puberty, it may be in progress several months before the other 
phenomena appear. 
In the adult state marked variations are found as regards the degree 
to which the sexual characters are developed. 
These need scarcely be specified, so commonly are they observed by 
physicians. 
They affect the breasts ; the pubic and axillary hairs ; the formation 
of the external genitals ; the type, quantity and duration of the men- 
strual discharge ; the psychical development. These differences exist 
between different races and between the various members of the same 
race. 
From the consideration of the many facts to vvhich I have referred 
we are forced, it seems to me, to regard the menstrual function as a 
highly specialised means, gradually produced, in the evolution of the 
highest mammals by which the two great factors in tissue metabolism 
—the anabolic and katabolic, are properly balanced. 
Normally it becomes established along with the various phenomena 
which characterise the development of sexual activity—at puberty, 
because it is then that the metabolic habit peculiar to females, viz., 
predominence of anabolism manifests itself. 
The rythmical character of the menstrual function has probably 
been gradually determined by the forces of evolution, and the marked 
range of variations which it presents in the human female (unasso- 
ciated with pathological conditions) points very strongly to an early 
period of instability in the process, preceding its present fairly fixed 
habit. It is, indeed, impossible for us to think of a rational explana- 
tion for the peculiarities which are found except on the ground of 
biological variations—atavistic reminiscences. 
The menstrual function, then, being closely correlated with the 
well recognized sexual characters is, like them, undoubtedly closely 
related to a nervous regulating mechanism, the nature of which is 
unknown as yet. There may be a special cord centre governed by 
still higher cortical centres, but there is also a subtle and intimate 
connection between the sexual functions and the general nervous 
mechanism of the body. 
As Johnstone ably states in regard to the uterus, “ its association 
with ovarian activity is that of two separate departments of an army, 
each of whose work must be thoroughly accomplished before the one 
common object can be attained. They are both controlled by branches 
from the sympathetic system, and instead of their actions being 
determined by each other, their orders come from that higher power 
which controls all functional activity.” 12 
It is this correlation which has been wrongly interpreted, especially 
in the case of the tubal and ovarian functions, with neither of which 
is the process directly connected. That it is indirectly related to 
them and capable of being influenced by them cannot be denied, and 
that of the whole sexual apparatus the ovaries are the “ predominant 
partner ” is not to be wondered at. We have proofs enough as regards 
their influence on body-metabolism, e. gin osteomalacia, marked 
improvement immediately follows removal of the ovaries. Whether 
this be due, as Ouratulo believes, to the secretion by these organs of 
a chemical substance capable of facilitating the oxidation of the phos- 
phoric organic substances supplying material for the bone salts, or, 
whether it acts merely by altering an ill-proportioned relationship 
between anabolic and katabolic functions, thus secondarily affecting 
the diseased process, is only a matter of speculation. 
After the removal of the ovaries in gynaecological practice, certain 
effects are noted, whieh must be associated with altered neuro-trophic 
functions. Thus “ heats ” or “ flushes,” vaso-motor storms are very 
often troublesome features. The uterus tends to shrink, the gland- 
tissue of the breast tends to atrophy, while fat is often increased in 
the body. There is, however, very great variation as regards the 
effect of removal on the sexual characters. These are so marked as to 
demand a careful investigation for the purpose of determining them 
accurately and of establishing a comparison between the bodily 
changes following the operation and those taking place in connection 
with the normal climacteric. At present many exaggerated ideas are 
current. 
While, in the majority of cases, removal of the ovaries is followed 
by an altered body-metabolism owing to the absence of the most 
important sexual organ, marked by disappearance of the anabolic 
overflow of menstruation, it is not surprising that variations should 
occur in the alterations produced, so that instances might occur in 
which the menstrual function does not cease. It is certainly not an 
uncommon experience to find discharges of blood from the uterus 
after the operation, apparently, an indication that the changes in 
body-metabolism are being brought about but gradually in these cases. 
As regards the relation of the tubes to menstruation, if Lawson 
Tait s observations be accurate, viz : that after their removal menstru- 
ation ceases in the great majority of cases, the ovaries being left 
behind, the explanation may be, either that such a marked alteration 
in the genital tract may reflexly alter all the sexual functions along 
with body-metabolism, or that it may bring about the result through 
an indirect influence (such as inhibition of function) on the ovaries. 13 
Bland Sutton’s statements as regards the effects of removal of the 
tubes are directly opposed to those of Lawson Tait. His words are, 
“ the Fallopian tubes exercise no influence on menstruation, and in 
order to produce artificial amenorrhoea both ovaries must be com- 
pletely removed.” I do not consider that Bland Sutton is justified in 
making these statements from the facts given by him. He quotes a 
few cases in which ligature of the tubes was performed without caus- 
ing a cessation of menstruation. Tait, however, speaks of removal of 
the tubes, a much more serious disturbance. 
Though there can be little doubt that menstruation has been estab- 
lished in the higher mammals by a gradual process of evolution, we 
have been entirely in the dark as to the steps of this process. Seeing 
that it is limited to the anthropidse and simiadse, the earliest appear- 
ance must have taken place among some common ancestors of both. 
The peculiarity probably first began as a variation, which proved 
to be advantageous and by natural selection became a fixed character, 
being transmitted from generation to generation. Had it been of no 
advantage it would have been eliminated. 
The only suggestion which has yet been advanced as to the possible 
advantage of this variation is that of W. E. Fothergill, who believes 
that it consisted in a greater tendency to conception owing to the 
rawing of the uterine mucosa. 
This suggestion cannot be entertained in the light of present know- 
ledge. We know that rawing of the surface is not necessary to the 
attachment and nidation of the fertilised ovum and that in the great 
mass of the mammals it does not occur. 
The introduction of menstruation in the evolution of the mam- 
malians has not been associated with greater but with diminished 
fertility, for there can be no doubt that the non-menstruating mam- 
mals are on the whole by far the most prolific. 
Indeed, natural selection, has acted in the highest ranks of the 
animal world not in the direction of establishing a numerical super- 
iority, but one based on the specialisation of individual characteristics 
in a selected number. 
The advantage of the variation in our distant progenitors must 
therefore be sought for in relation to factors tending to diminish the 
number of offspring and to improve the quality of the individual. 
As to the origin of the variation, the only reasonable speculation 
seems to be that it is associated with the development of the single 
uterus, with the diminution in the number of offspring, with the 
determination of the semi-erect or erect posture, characteristics found 
throughout the Primates, at least in the simiadse and anthropkke. 14 
(The division of the Primates, known as the lemuridse, stands by itself. 
These forms are believed not to be in the direct line of the other 
divisions but a separate offshoot from some early common mammalian 
stock. They have a double uterus and, so far as we know, do not 
menstruate.) 
Of prime importance I believe, among these factors is the ehange 
from the bicornuate to the single condition of uterus. In the great 
mass of mammals with the former variety, the excess of anabolism is 
used up in the large demands of breeding and nursing. When the 
single uterus appeared as a variation marked by a diminished area for 
the attachment of ova, the unused anabolism found an outlet in the 
escape of blood. 
It is possible that this took place at first from different parts of the 
body thus helping to explain the occasional occurrence in females of 
vicarious menstruation.” 
If this were the case, natural selection must have acted in eliminat- 
ing all except those in whom the blood escaped from the uterus. 
But it is also likely that the tendency to sit on the ischial tuberosi- 
ties and to move about more or less in the semi-erect position may 
have somewhat determined the occurrence of the congestion chiefly in 
the pelvis, relief being found by a discharge from the delicate mucosa. 
The blending of two blood-supplies in a single uterus, which had 
previously been distributed to two cornua, must have had an influence 
in inducing a special tendency to uterine congestion. 
Probably also another factor helped to determine the localisation of 
the congestion to the pelvis, viz: the habit already fixed among many 
of the lower mammals of the periodic pelvic congestion of the rutting 
period. 
In the beginning it is likely that the menstrual discharge took place 
at irregular intervals (thus explaining the occasional irregular types 
which are now found among females.) 
Natural selection would here come into play in determining regu- 
larity of type. 
Females who were irregular in regard to the discharge would be 
objects of inconvenience to the males who would very soon learn to 
seek out and prefer those whose unseemliness manifested itself only 
at expected and definite periods, and so gradually regularity would 
come to be the predominent feature in succeeding generations of off- 
spring. 
It is a striking fact that among all races there is a careful avoid- 
ance of menstruating females by the males. "This is particularly 
marked in most primitive peoples. Very possibly it had its origin in 15 
a feeling of disgust on the part of the males, and it is not difficult to 
understand how among the earliest human beings, there might grad- 
ually develop the belief that women were possessed of some unclean 
or evil spirit which had to escape periodically. 
It is thus easy to explain the universal though varied customs and 
practices prevalent in many races, by which the woman is forced at 
her periods to avoid association with others, to abstain from coitus 
with men and to withdraw even from observation in order that her 
evil influence might not spread. 
Next, it is of great interest to inquire into the possible gains that 
might result from the fixing of the menstrual process in females. 
It is a remarkable fact that in the highest mammals, viz: the 
simiadae and anthropidse, is found the highest development of the 
altruistic principle as exhibited between parents and offspring. As 
Westermarck points out, among the invertebrata the male is interested 
only in the act of fertilisation, while the female shows no further con- 
cern or responsibility after she has laid her eggs. In the lower verte- 
brata parental care is almost unknown, though there are a few excep- 
tions, e. g., chiefly in the chelonia ; the males caring for the young in 
some cases, the females in others, while in a few instances there is 
joint parental attention. 
In the birds, however, it is the rule that the parents live in most 
intimate relationship, both during and after the breeding season, the 
female hatching and rearing, the male acting as protector and provider 
of food. 
Among the great mass of mammalians, below the primates this is 
not the case ; the mothers alone showing great concern for the young 
offspring while generally the males are only interested in the females 
at the rutting time. 
Exceptions are, however, found e. g., among whales, seals, certain 
deer, moles, squirrels and a few other forms ; the parents remain 
together after the birth of the young, the male acting as protector. 
Among the Primates the rule is that the males and females unite 
in a more or less enduring partnership, both having great concern for 
•the care of the offspring, the males possessing one or more wives. 
There is an abundance of facts to establish this statement and from 
them Westermarck has established his induction in a masterly work, 
that our human marriage is an inheritance from an ape-like ancestor, 
controverting the lone' held belief of Sir John Lubbock and others that 
our progenitors formed one vast free-love community where promis- 
cuity of sexual intercourse prevailed. 
This habit is therefore another interesting posssession of mammals 16 
with a single uterus. It marks a great advance in the character of 
the individual above the types found in the lower orders of animal 
life. 
Very evidently it was fostered by means of natural selection, being 
most essential where the female gave birth to a small number of young 
who passed a long time in a state of helpless infancy and tutelage. 
Such a species, undoubtedly, stands a better chance of surviving when 
the parents unite their energies in the task of protecting and nurtur- 
ing the offspring. 
Indeed, it would appear that the great determining factor of con- 
jugal relationship is care for the young. Among several primitive 
races (and in some of the highest) marriage is never supposed to be 
established until offspring appear. 
Wherever in the animal kingdom we find that the parents have no 
concern with their offspring, the females give birth to a very large 
number of offspring—the prodigality of births allowing of the safe- 
guarding of the preservation, of the species. Thus the cod lays each 
year about a million eggs, to which she gives no after-care, and, 
probably, the greater number become destroyed. On the other hand 
the turtle-dove lays only two eggs, but owing to the care which the 
parents give to the young they generally grow to maturity. 
Another important point to notice regarding intercourse between the 
sexes, is that while among the majority of mammals there are special 
times of pairing, conditioned by various necessities, different in differ- 
ent species, among the quadrumana the rule is probable that fruitful 
intercourse may take place at any time, though undoubtedly excep- 
tions occur owing to conditions of food, environment, etc. In the 
evolution, therefore, of the higher mammals possessing one uterus, 
there has been a departure from the condition of periodic excesses of 
sexual rioting to one in which there is especially in the female, a more 
diffuse and consequently less intense manifestation of the sex instinct. 
The menstrual function occurring regularly in animals so placed, 
must have served beneficially in giving the mothers continually re- 
curring periods of ensured rest (for so far as we know coitus is uni- 
versally desisted from during menstruation) and in teaching the males 
continual lessons in self-restraint. 
Relation of Menstruation to Rut.—There is a wide-spread belief 
that these phenomena are identical. Thus a very recent writer 
(Letourneau) states that “ menstruation is essentially identical with 
the intimate phenomena of rut in the females of mammals and corre- 
sponds to an ovarian congestion, or to the swelling and bursting of 
one or more Graafian follicles. A few writers have in recent years 17 
disputed this view, among whom may be chiefly mentioned Lawson 
Tait. 
There are many who believe that the rut or cestrus£ or pairing time, 
is conditioned by ovulation—that ova are only shed at these intervals 
causing the phenomena. There is no basis of facts for this statement. 
The examination of many rutting animals proves that ovulation goes 
on at all times. The origin and significance of rut are uncertain, but 
it seems probable that the habit has been developed by natural 
selection for the purpose of limiting the chance of fertilisation to 
certain seasons mainly with reference to dietetic and climatic require- 
ments for the offspring. 
Among the mammalians this period is found at all times of the 
year. Thus, the bat pairs in January and February ; the wild cat and 
fox in February ; the weasel in March ; the musk ox in August ; the 
badger in October ; the orongo-antelope in November and December. 
When the different cases are enquired into it will be found that the 
time of pairing is related to the duration of pregnancy, it being neces- 
sary that the young should be born at a time when they stand the 
best chance of living. 
Thus the majority of mammals produce offspring early in the year ; 
in the tropics at the beginning of the rainy season—the time of birth 
evidently being related to abundance of food, water, warmth of 
climate, conditions most favourable to existence. In polar and tem- 
perate regions the animals pair at a later period than in warm coun- 
tries. These differences are seen when the same species are placed 
under different climatic conditions. 
When no definite pairing system exists, as among elephants, whales, 
many rodents, the explanation is very evident. The conditions of 
their environment and of their food supply are such as not to necessi- 
tate the birth of offspring at special times. 
Among the primates it is doubtful if there is a rutting season among 
many species. It is stated by some observers that it exists in the 
orang-outang and gorilla. In general it is to be expected that in the 
simiadse and anthropidse, whose food supply is of a much more diverse 
nature than in the lower mammalians, consisting of animal and vege- 
table matter in different forms, there is no necessity for the birth of 
offspring at special times. Moreover, it must be remembered that the 
anxious time as regards the newly born does not last only for a few 
months after birth in the simiadse, but for years, the period of infancy 
being long just as in the case of homo. It is therefore likely that as 
far as food requirements are concerned one season is as propitious as 
another for birth. 18 
Another important factor must be borne in mind, viz : that where 
there is a strong development of parental affection and conjoint par- 
ental care for the young, an important additional reason exists for 
diminishing the necessity of special pairing seasons. This is all the 
more marked in the anthropidse where, owing to a higher intelligence, 
individuals learn to combat the injurious influences of their environ- 
ment and to make it possible for the offspring to have as good a 
chance of surviving at one time of the year as at another. 
If then, there be found exceptional cases of special pairing season 
among the higher primates, it must be because natural selection has 
conserved the habit in relation to the special conditions in which those 
species are placed. 
Among the reptilians and birds, the rule is that pairing occurs in the 
spring, and it is probable, that, as Westermarck points out, the world- 
wide association of the springtime with the awakening of sexual 
affinities has been based upon the observations made mainly on birds. 
The modifications in the pairing season which can be induced by 
artificial means, e. g., domestication, are a strong evidence in favour of 
the influence of external influences on reproduction among the higher 
vertebrata. Indeed, it is evident that just as rut becomes adapted to 
the requirements of separate species, so it may become altered in 
relation to the needs of individuals under varying conditions. 
Another interesting fact must be mentioned viz : that while the 
rutting-period is practically the only time when the females will 
copulate with the males, the menstrual period is the time above all other 
periods when they will not engage in this act. This is universal among 
mankind and is true for the simiadee as far as our observations go. 
Moreover, the changes in connection with rut result among other 
things in softening and dilating the outer genitals for the reception of 
the penis, they being at other times in many animals too much con- 
stricted for this. It is well-known that a bitch will not generally 
allow the dog near her until the rut has been in progress for a time, 
i. e., until the vulva and vagina are sufficiently dilated. 
So far as our facts go, it seems likely that rut in the higher verte- 
brates is merely the expression of the force of sexual affinity necessary 
to ensure fertilisation of the ovum, which is found throughout the 
whole animal kingdom, diffusely spread in the lower forms, highly 
specialised and limited in the upper forms owing to the influences of 
environment and natural selection, and affecting both males and 
females alike. This participation of the males is important to bear in 
mind. It is found everywhere. Thus many fishes when the love 
period arrives put on brilliant colours, become vigorous and play about 19 
among the females in the most lively fashion—evidently in a state of 
sexual excitement. In some, e. g., the stickleback and salmon great 
pugnacity is manifest. The male salmon develops a special crook in 
connection with the lower jaw at this time, while the teeth enlarge, 
markedly. Among many amphibians also many changes affect the 
males, sexual desire becoming very marked. Among the reptilia similar 
changes occur, the male tortoise for example being fierce and noisy. 
In snakes the scent-glands become active during the pairing-season. 
Anions the birds the changes in the love-season are very marked. 
The male is altered in various ways and takes to dancing, coquetting 
and to vocal and instrumental music. His scent-glands grow active ; 
his ornaments become more marked, and he developes strong fighting 
tendencies. 
Among mammals the intensification of sexual desire in the males, 
accompanied with a feeling of jealousy and a keenness to fight, is 
universal. In all orders the voice is used in the rutting-time more 
than in any other season. Indeed, the porcupine and giraffe are said 
to be mute at all other periods. In stags the larynx and thyroid 
enlarge when rut comes on. The nose of the male sea-serpent becomes 
greatly enlongated. In the bladder-nose seal the hood covering the 
head becomes markedly inflated. Scent-glands emit strong odours. In 
some cases the colour of the skin changes. Among the great majority 
of females no such marked changes occur. They play their normal 
role of passivity, the changes brought about by the wave of sexual 
excitement being mainly psychical. 
In many mammalians the only physical changes recognizable at the 
oestrus are congestion of the soft parts in the pelvis, dilatation of the 
vulva and the vagina, and the free discharge of mucus which is often 
blood-stained. These differences between males and females in regard 
to the rutting period are in keeping with the organic distinction to 
which I have so often referred in this paper. 
The manifold changes in the males are the outcome of their pre- 
dominant katabolism. 
The females need to conserve their energies, i.e., their anabolic 
surplus, for the strain of pregnancy ; consequently there is no waste 
in outward exuberant manifestations, except in very slight measure 
in the cases to which I have just alluded. 
Finally, it may be stated that the relation of rut to menstruation 
in mammalian evolution is simply this—that when, owing to the 
various reasons which I have elaborated in an earlier part of this 
paper, menstruation appeared as a new variation, one of the factors in 
determining the escape of the anabolic overplus by way of the genital 
tract was the habit already fixed, in many of the mammalians with a 
bicornuate uterus of the periodic yearly pelvic congestion of the 
rutting time.