■u
'     #*4-****
■***f"i
k <V
l^r-
c.?***-
 
Surgeon  General's Office
r 
 
 
                        AN

       INAUGURAL DISSERTATION,

                      ON THE


Analogy  between  Plants and Animals.

                    SUBMITTED

               TO THE EXAMINATION

                      OF THE

           REV.  JOHN ANDREWS, D. D.

                  PROVOST PRO TEMP.

   THE MEDICAL PROFESSORS AND TRUSTEES,

                        OF

        THE UNIVERSITY OF PENNSYLVANIA,

              On the 21st day of April, 1806;

                     FOR THE

  DEGREE  OF DOCTOR  OF MEDICINE.

                   —        /W;^h  f

             BY  WILLIAM F.  SELBY,

                   OF MARYLAND,       ' ,; ^,'j~jfT''^ ^ jV5

     MEMBER OF THE PHILADELPHIA MEDICAL SOCIETY.
Valisner sits, up turns her tearful eyes,
Culls her soft lover, and upbraids the skies:
For him she breathes the silent sigh forlorn,
Each setting day ; for him each rising morn.
                     Darwin's Bot. Garden.
K    }~~ff-
    PHILADELPHIA:

PRINTED FOR THE AUTHOR.
1806. 
 
     TO DOCTOR SAMUEL KER,




                OF MARYLAND.







    GRATITUDE calls on me to name you the



first on the list, of my medical fathers.....As un-



der your auspices, I commenced my medical stu-



dies;  and from your  communicative talents,  I



have received much pleasure and advantage.....



This  is  inscribed  as  a  small  testimony of the



great regard, and friendship of  your former pu-



pil, and ever grateful friend,




                            THE AUTHOR. 
 
    TO JOHN CHURCH, M. D.





         OF PHILADELPHIA,




THIS IS INSCRIBED, AS A SMALL MEMORIAL




                OF




 THE FRIENDSHIP AND POLITENESS




   WITH WHICH YOU HAVE HONORED





          THE AUTHOR. 
 
TO WILLIAM SHIPPEN,  M. D.
    Adjunct Professor of Anatomy and Midwifery.

TO BENJAMIN RUSH, M. D.
\    Professor of tbe Institutes, Clinical Cases, and
           of tbe Practice oj Medicine.

TO CASPAR  WISTAR, M. D.
    Adjunct Professor of Anatomy and Midwifery.

TO JAMES WOODHOUSE,  M. D.
    Professor of Chemistry,
                    AND
TO PHILIP S. PHYSICK,
    Professor of Surgery,
                THIS IS INSCRIBED,
            AS A SMALL TRIBUTE
        OF THE GREAT RESPECT DUE TO YOU,
                          BY
                             THE AUTHOR. 
 
DISSERTATION
Analogy between Plants and Animals.
THE  similarity  of some plants  to  animals,  has
attracted the attention of philosophers since the  time
of the ancient Pythagoras—-This great and ingenious
man was so deeply impressed with this sentiment, that
he abstained from several species of vegetables on ac-
count of their affinity to animals.   An investigation of
this analogy has lately very much increased:  and as
science has enlightened the world, many of those  dark
clouds have been dispelled that have long obscured this
part of nature.   Linnaeus and others, by tracing their
similarity to animals in  the identity  of propagation,
have thrown much light on this subject.
                        B 
10
  We will now proceed to mention a few of their most
obvious analogies:
                    PLANTS
are organised,  living bodies; they are composed of
solids and fluids-their solids are composed of an in-
tertexture of  fibres,  constituting their membranes,
muscles, and their different kinds of vessels, circula-
tory,  secretory, and absorbing.

   OF THE  INTEGUMENTS OF PLANTS.

   Plants have their different integuments and layers of
skin.

   1st. Is their epidermis or  cuticle,  this is the most
external.

   2nd.  Is their cortex, which is of a fibrous structure.

   3rd. Is their liber.  This is also fibrous, and imme-
diately surrounds the wood.

   These folds of skin,  are  to plants, what cuticula,
rete mucosum, and cutis vera, are to animals, namely,
to defend their internal parts, which are tender, from
exposure to inclemency of weather, and to defend them
from  the attack  of enemies;  and in order to do this
completely, Nature has wisely given  thorns as defen-
sive weapons to some plants that are most exposed. 
11
       OF THE  VESSELS OF  PLANTS.

   Plants, like animals, have their circulatory, secreto-
ry, and  absorbing vessels:  and  these have been di-
vided into many others.

   Their absorbent vessels,  take their  nourishment
from the air, water, and earth, and convey into their
systems.

   Their circulatory vessels  carry  this fluid through
their  different parts and glands,  and is then  thrown
into their secretory vessels, by which it is converted
from  a bland and inodorous fluid, into one  that is
powerful in smell, taste, &c.   These vessels also se-
crete  the different  gums and resins, some of which are
so highly important to man.

    OF  THE  ORGANS  OF GENERATION
                  IN PLANTS.

   Linnaeus,  in his sexual system, has given to plants
their  different  organs  of generation,  appropriated  to
their different sexes: these parts in the male are called
stamens, the component parts of which are,  filamen-
tum, anthera, and  pollen; the female organs are called
pistils,  these are  divided  into germen, stylus,  and
stigma.   The  use of these parts we shall speak  of
presently. 
12
    OF THE RESPIRATION  OF PLANTS.

  How plants could respire, was once an idea beyond
comprehension,  but is now proven  that plants do re-
spire;  and botanists  no longer disagree on this sub-
ject, but only dispute on the part of the plant perform-
ing this very important function.

  Some have contended that  respiration went on in
the leaves, while Dr. Darwin very ingeniously argued
to prove that respiration was carried on by the corolla,
or corol, and has very plausibly compared this part to
the lungs  of animals;  however, let this question be as
it will,  we can certainly prove that plants  do respire,
and that respiration seems to be performed by several
parts of the plant.  It was first imagined that all plants
discharged oxygen gas in their  expirations, and on
this theory they  were  supposed to add to the purity of
the atmosphere; but this opinion  has been ingeniously
disproven by professor Woodhouse, who has evidently
demonstrated that some plants discharge azotic gas.

   Dr. Hales, in a series of elegant experiments, has
proven that their tracheae are  also circulatory vessels.
See his Vegetable Statics.

   Dr. Keill, by estimating the quantities of the seve-
ral evacuations of his body, ascertained that he eat and
drank every  24 hours, 4 pounds 10 ounces.  In the ex- 
13
periments of Dr. Hales, the sun flower imbibed and
perspired  in  the same  time 22 ounces;  so a man's
food to that of the sun  flower, is as 74 to 22 ounces,
or as 7 : 2.....But compared bulk for bulk, the plant
imbibed 17 times more fresh food than the man: for
deducting 5 ounces which  Dr. Keill allowed for the
fceces alvi, there remains 4 pounds 5 ounces of fresh
liquor which enters a man's veins, and an  equal quan-
tity passes off every 24 hours; then it will be found,
that 17 times more new fluid enters the sap vessels of
the plant and passes  off in 24 hours, than enters the
veins of a man and passes off in the same time.  See
the same.

    OF THE COMPOSITION OF  PLANTS.

   Of the composition of plants it is unnecessary to say
much,  as  Modern Chemistry has proven that some
plants possess all the constituent parts of animals, such
as azote, hydrogen, carbon, sulphur, phosphorus, and
ammonia.  See Lavoisier's  Chemistry.

    OF  THE LOCOMOTION OF  PLANTS.

   Some have supposed  that the power of  locomotion
should be  a line of distinction  between  plants and ani-
mals. But those e*entlemen should have reflected, that
there are several  animals which possess this incapabi-
lity ; but if we should even allow all animals to be pos- 
14
sessed of this faculty,  we also find  that several plants
have this power of locomotion.  The male flowers of
Valisneria  detach themselves from  the parent plant,
and  float on the surface  of the water  to  the female
ones.  See Botanic Garden,  Part ii, art. Valisneria.

    OF THE IRRITABILITY OF  PLANTS.

  If we  deny to plants the  faculty  of irritability,  of
what use would  all these different systems of vessels
be ?  Nature never did any thing in vain.  How would
plants be enabled to perform all their different excre-
tions and secretions, such as gums,  resins, when they
are  deprived of irritability? If plants have life, which
the greatest sceptic cannot dare to deny, how can it be
supposed that life should commence or  continue inde-
pendent  of  irritability ?  For to think  of life  without
irritability  is impossible.   We also  infer their irrita-
bility from  touching the mimosa or sensitive  plant,
which is known  by every one to contract immediately.

  The Dionoea  Muscipula or Venus's fly trap, is a
very remarkable  instance of vegetable irritability.   Its
leaves are  armed with  spines  or thorns,  on its upper
edge,  and  are  spread on  the ground around  their
stems;  when an  insect creeps  on any of them,  on its
passage to the flower or seed, its leaves immediately
close like a steel rat trap,  and strangles the  unfortu-
nate victim.  Having now  proven  that they possess 
15
irritability,  we are from  this point led to  one more
important, which is their sensibility. Many obstinate
facts appear to demand our belief in this opinion,  as
plants  seem to have their loves.   Botanists have ob-
served, that many species of plants, both female and
male, leave their  parent stock and go in  search of their
paramours.  This leads us to a very plausible opinion
that plants have their own ideas.  They have certainly
the senses of heat and cold, and  of dryness  and mois-
ture.   Some plants close  their petals and calyxes dur-
ing the cold parts of the day;  others, after suffering a
long time for rain, are known to  open every part of
them when  a plentiful supply  of it has arrived, and
imbibe it greedily.  This cannot  be explained by irri-
tation,  as that would  have  a  contrary  effect, namely
contraction;  and their petals and  calyxes  would be
closed  instead of being  opened.   And how can we
explain this phenomenon, if we do not suppose it was
in consequence of  their  feeling  too much cold and
dryness ?

  With what  avidity  do  the tendrils of many vines,
which  are fond of ascending,  grasp a neighbour who
is taller than themselves,  and frequently become disa-
greeable and injurious companions to  their new and
passive acquaintances.  And I am informed  that seve-
ral of this species have been known to turn and change
their direction, in order to grasp a pole that has been
fixed near them in the ground. 
16
  If we permit them to have these different motions,
and the senses of heat and  cold; and  as the senses,
through the whole series of animated nature, are the
only avenues of knowledge;  and as no sense is given
without a  capability of receiving  ideas through the
medium of that sense; why should plants, possessing
those organs of sense, be deprived of the faculty of
possessing  ideas,  and consequent thinking?

  With all these faculties  existing in them certainly,
but in a subordinate degree, let us examine how these
degraded beings  begin, continue, and cease to live.
We have before mentioned their passion of love.....
This  passion  excites the males and females to ap-
proach each other.  That  stimulus of procreation, so
necessary for the continuation of all animated nature,
propells them on to embrace each other.   The germ
of the female becomes impregnated,  after receiving
the Pollen,  or vivifying powder from the male.  The
little embVyo is thus wisely enveloped in its own peri-
carp, and  is then ready,  when  implanted in a proper
soil,  to come forward in the world, and begin his ca-
reer of life.

   In order to examine the  situation of the embryo,
and to trace its  analogy to animals in its foetal state,
I determined to make some experiments for this pur-
pose,  on Zea mays, or our Indian corn.   But before
entering on a series of these experiments, it would be 
17
necessary to give some  description of the anatomy of
thib grain. The parts composing a grain of this corn
are four:  viz.

   1st. A flinty substance, which is external, being very
thin  at  the top of the  grain,  but becomes gradually
thicker and larger on both sides, down to the lowest and
smallest end of the grain.

   2nd.  Is a substance  soft and farinaceous, which is
much thicker and wider on the top, lies under the ex-
ternal substance, and decreases downwards, in propor-
tion  as  the  former,  or  external,  substance  increases.

   3rd.  Is that  portion  called  the %heart, by farmers;
this begins at a small distance from the top of the grain,
and gradually widens towards the bottom and ends, very
near the lowest  end  of the grain; this  occupies  the
middle  space, and  shall say is placed on the anterior
side  of  the grain.

   4th.  Is the part, I have ventured to call the embryo,
or corcle, which runs longitudinally through the whole
substance of the  third portion, or heart.

   On the 29th of April, 1805, I took seven grains of
this corn; of these seven grains the first,

       No. 1. had the lower end  pared off till the era-
                         c 
18
bryo or corcle, which terminates very near the lower
end of the grain,  was brought into view.

       No. 2. had a considerable portion of the grain
taken off near the heart or third division, by a trans-
verse incision made through the top; and with a lon-
gitudinal incision on the side, exposed the heart, with
a very minute portion of it taken off on the side.

       No. 3. had the top of the grain pared off to the
same distance with the last, and with a lateral incision
took off nearly half the heart, with the whole substance
of the grain as far as that part.

       No. 4. had a considerable portion of the exter-
nal substances, with  the  whole heart and corcle re-
moved.

       No. 5. had rather more of the  external sub-
stances removed  than  in the last  experiment, but its
heart and corcle remained uninjured.

       No. 6. had all the surrounding substances re-
moved as nearly as possible from the heart.

       No. 7. had nothing but the  heart and corcle
removed.

   On  the same day (29th of April),  planting each in 
19
 regular order, with a stick by each, marking carefully
 the different numbers.
   On the 12th of May the succeeding month, No.s 1
 and 5 appeared above the surface of the ground, No.
 1 appearing  somewhat the largest; No. 2 appeared a
 few days after;  none of the rest ever appeared.   In
 this stage of existence, the analogy between plants and
 animals is strikingly obvious in the 1st and 2nd  expe-
 riments, but more particularly  in the 5th.  As in this
 experiment a great  part  of those substances was re-
 moved,  constituting what may with  strict propriety
 be termed placenta of vegetables, while the heart and
 embryo or corcle was unimpaired.  And in this  expe-
 riment we have reason to suppose that there was  a suf-
 ficiency of placenta  remaining to carry an absorption
 for the  nourishment of the foetus: for this grain came
 forward as soon as No. 1, which had only a very small
 portion of its lower end removed; and although a larger
 proportion of the  surrounding substances of No.  5 was
 removed than in  No. 2,  we find that No. 5 came for-
 ward the soonest: and we can  only account for  it but
 by recollecting that No. 5 had its embryo, and also the
 substance immediately investing its embryo uninjured,
 while No. 2 had but a very minute portion of its third
 division  or heart  removed, but this small part consi-
 derably delayed the  grain in coming  forward.  And
 from these experiments it also appears, that the nearer
we approach the foetus, the more  vital are those  parts
 which immediately invest it. 
20
  As we know it impossible for an animal foetus to
come forward to maturity without its  proper mem-
branes and placenta:  in the same manner  we find it
impossible for a vegetable foetus, when deprived of
these parts, to arrive  at perfection; for  in No. 6, we
there find this little being deprived of its placenta,  ne-
ver to advance to perfection.  And in No. 7, we might
as well have expected  that a placenta could be convert-
ed into a foetus, as that this grain should come forward
after being deprived of its  embryo; it might with some
propriety be compared to an abortion with the placenta
in utero.

  We have from these experiments  proven very de-
cidedly,  that  this 4th  division, contained in the heart,
is the punctun saliens embryo or corcle.

  That in the 1st experiment we have shewn that  a
small portion of its placenta might be removed and the
grain still succeed tolerably well in coming forward;
and in the second experiment, that a considerable por-
tion of its two external surrounding substances, and a
very small portion of its third substance  or heart might
also be removed, and the  grain, with some little inter-
ruption,  still  come forward; and that we should not be
surprised at No.s 3 and 4 not coming forward, as the
former lost a considerable portion of its foetus, with a
quantity of its placenta; while the latter lost the whole
of its embryo, with some of its placenta.   And that in 
21
No. 5 we have ascertained, that if the heart and corcle,
being unhurt, the grain would come forward, after hav-
ing lost a considerable portion of its placenta. And that
in No. 6, the grain, although having its heart and cor-
cle uninjured, could never come forward to perfection,
on account of its want of placenta.

  And  upon  the whole, that plants may possibly lose
more  of their placenta than  several animals,  and still
succeed in arriving at perfection;  and that the foetus is
the fourth division of the grain, and that it can never be
touched without injury.

  We have now seen plants invested by their own mem-
branes and placenta,  imbedded in the earth,  and there
capable of being stimulated, even at this  early period of
existence,  to assume  the form of life, and to become
perfect and well grown. We also behold them like ani-
mals, have venereal desires,  so necessary for the conti-
nuation of their species.  We have also seen the  stimu-
lus of hunger, thirst, as well as that of procreation, act-
ing on their excitabilities, and these stimuli producing
certain  motions and contractions; as they have  an ex-
citability, stimulus acting on this excitability,  must
produce the motions  of life___this excitability is at all
times capable of being exhausted by stimulus....life
must be in them as in animals, a forced state.   If
then stimulus, acting on excitability,  produces life, a
due proportion  of their  excitement  and  excitability 
22
  will constitute their perfect health; and if at any time
  this balance is lost, disease or predisposition to disease
  must be the inevitable consequence.

    For example,  if too much stimulus has  acted  on
  their excitability, violent or morbid excitement is the
  consequence constituting their forms of disease, termed,
  inflammatory, or of too much action.

    These forms of disease are exemplified by their ex-
  posure to violent heat,  as when they are  too strongly
  stimulated by the scorching heat of the sun, in a dry
—summer; or from an e-wtjMMftie-n of strong nourishment
  given them in the form of green and stimulating manure.
  Their surfaces appear red, dry, and parched,  having in
  fine every symptom of fever.  The cure should  be as
  with animals:  abstract stimulus,  moderate excitement,
  by cool air, cold and diluting drinks; this is done for
  them, very fortunately, by  a happy shower of rain....
  Plants have,  in common with animals, their opposite
  forms of disease: when growing in  dark and  shady
  places, they have been observed to be  pale and weakly,
  on account of their want of the grateful stimulus of light
  and heat, a stimulus by no means inconsiderable in the
  animal world.  In  this case, as with animals, restore
  the usual and  required stimulus.

    Give them tonics and stimulants, in the  forms of the
  different remedies, termed  by the farmers,  manures; 
23
but we should take care to begin with small doses, if
their excitability is much accumulated, else we elevate
their excitement too high; for plants, when suddenly
cooled by a shower of rain in  the summer, have their
excitabilities very  much accumulated; and if the sun
begins to shine with its usual warmth and splendor im-
mediately after the rain,   they  become  parched and
burnt, in  consequence of their violent excitement.
Plants are also subject to disease in its  many various
forms, called by the farmers, rust, scab, Sec. They are
subject to their disorders or local affections....these are
exemplified in blotches, specks, &c. On a  proper know-
ledge of their many various forms of disease,  rests the
whole science of agriculture.  And here a large field of
useful inquiry is laid open for  some happy experimen-
ter.   And I make no doubt, but that period will arrive,
when we  shall learn  to prescribe,  with  as much  ad-
vantage for a sick plant as for a sick person.

  We have now considered plants in their foetal stage
of existence, and  advancing from  that state  like ani-
mals  to their proper growth, and then to answer  the
purposes of their  creation, by  providing  themselves
with successors; and then to make their  exit....Death
the common lot of man, as well as that of every other
animated being, must be the consequence of the same
causes in plants as in animals,  namely from an exhaus-
tion of excitability, or from a want of excitement....
Man  and  other animals,  bring on  their  disease, fre- 
24
   quently by an improper use of their different appetites
   and passions.   Botanists have  observed, that  p ants
   when deprived of the faculty of fecundation, are apt to
   live longer....Probably like some animals, they are too
   much disposed to venereal pleasures, and often curtail
   the span of their existence, by-immoderate sacrifices to
   the votaries of Venus. Like animals, many die as soon
   as they begin to live.  Myriads of them, as soon as they
   raise their heads above the surface of the earth, are de-
   stroyed by the mouths and feet of many ravenous ani-
   mals; while other promising little sprouts, bidding fair-
   to be the monarchs of the forest, have fallen premature
-   victims to the overtowering hand of man.

      After tracing plants from their most early period of
   existence;  considering their many various faculties,
   motions, and  senses, where shall we draw the line of
   distinction? This line cannot yet  be drawn; but that
   time probably will arrive,  when this long sought for
   boundary shall be discovered.

      With what order and uniformity do the laws of na-
   ture exist, through the vast fabric of creation,  every
   part thereof plainly  demonstrating that we are all the
   offspring of the same parent.
THE END. 
 
 
Me-i.Wist.
   WZ-


 not
t<\ 
		J: Ce"
		i
'*&		
		r
l*fc		
.«*y :•**'■   *Sf
-'■•^