[From the Proceedings ok tub American Association for tiik Ar>vancemknt 
of Science, Vol. XXXI, Montreal Meeting, August, 1882.J 
Observations on tiik Fertilization oe Yucca and on stuuciural 
'A ND ANATOMICAL PkCULT ARITIES IN PrONUBA AND PllODOXL’S. 
By C. V. Riley, of Washington, I). C. 
This paper records some recent experiments and observations 
which establish fully and conclusively the fact that Pronuba is 
necessary to the fertilization of the capsular Yuccas. It describes 
for the first time how the pollen is gathered and collected by the 
female Pronuba. The act is as deliberate and wonderful as that 
of pollination. Going to the top of a stamen she stretches her ten- 
tacles to the utmost on the opposite side of the anther, presses the 
head down upon the pollen and scrapes it together l>3r a horizontal 
motion of her maxillae. The head is then raised and the front 
legs are used to shape the grains into a pellet, the tentacles coiling 
and uncoiling meanwhile. She thus goes from one to another until 
she has a sufficiency. 
My observations confirm the accuracy of Dr. Geo. Engelmann’s 
conclusion as to the impotence of the stigmatic apices in some of 
the Yuccas and show how the apparently contradictory experience 
of Mr. Meehan can be reconciled on variation in this respect in 
the species of the same genus. The exceptional self-fertilization 
in Yucca aloifolia — the only species in which it is recorded — is 
shown to be due to the fact that in the fruit of this species, there 
is no style, the stigma being sessile and the nectar abundant, filling 
and even bulging out of the shallow opening or tube. The flowers 
are always pendulous and the pollen falling from anthers, under 
favorable circumstances, readily lodges on the nectar. 
The irregularity in the shape of the fruit of the Yuccas — con- 
sidered a characteristic by botanists — is proved by experiments 
to be due to the punctures of Pronuba. 
The egg of Pronuba which averages 1.5 mm. long, having a 
swollen apical end and a long and variable pedicel is passed into 
the ovarian cavity. The puncture is made usually just below the 
middle of the pistil on the deeper depression which marks the true 
dissepiment, or through the thinnest part of the wall. The horny 
part of the ovipositor reaches the longitudinal cavity at the external 
base of the ovule near the funiculus, without, as a rule, penetrating 
or touching the ovule itself, and the delicate and extensile oviduct 
then conveys the egg for some distance (the length of six or eight 
ovules) along the cavity, the terminal portion of the oviduct being 
[abstract.] 
467 468 
hibernation of aletia ; by c. v. RILEY. 
furnished with retrorse hairs which help to hold it in place during 
the act. 
The paper concludes with some studios of the internal anatomy 
of Pronuba and Prodoxus. 
The Hibernation of Ai.etia xylina (Say), in the United 
States a settled fact. By C. V. Riley, of Washington, 
D. C. 
[ABSTRACT.] 
I have already shown in previous remarks before the Association 
that there were various theories held by competent men — both 
entomologists and planters — as to the hibernation of this Aletia 
(the common cotton worm of the south) ; some believing that it 
hibernated in the chrysalis state, some that it survived in the moth 
state, while still others contended that it did not hibernate at all 
in the United States. I have always contended that the moth 
survived within the limits of the United States, and in this paper 
the fact of its hibernation, principally under the shelter of rank 
wire-grass, is established from observations and experiments made 
during the past winter and spring. The moth has been taken at 
Archer, Fla., during every winter month until the early part of 
March when it began to disappear, but not until eggs were found 
deposited. The lirst brood of worms was found of all sizes during 
the latter part of the same month on rattoon cotton, while chrys- 
alides and fresh moths were obtained during the early part of April. 
The fact thus established has this important practical bearing: 
Whereas, upon the theory of annual invasion from some exotic 
country there was no incentive to winter or spring work looking to 
the destruction of the moth, there is now every incentive to such 
action as will destroy it either by attracting it during mild winter 
weather by sweets, or by burning the grasses in which it shelters. 
It should also be a warning to cotton growers to abandon the slov- 
enly method of cultivation which leaves the old cotton stalks 
standing either until the next crop is planted or long after that 
event, for many planters have the habit of planting the seed in a 
furrow between the old rows of stalks. The most careful recent 
researches all tend to confirm the belief that Gossypium is the only insecticides ; ry c. v. riley. 
469 
plant upon which the worm feeds within the cotton belt; so that 
in the light of the facts presented there is all the greater incentive 
to that mode of culture which will prevent the growth of rattoon 
cotton, since it is questionable whether the moth would survive 
long enough to perpetuate itself upon newly sown cotton except 
for the intervention of the rattoon cotton. 
Emulsions of Petroleum and their value as Insecticides. By 
C. V. Riley, of Washington, I). C. 
[ABSTRACT.] 
The value of petroleum for the destruction of insects has long 
been recognized and I have for years been endeavoring to solve 
the question of its safe and ready use for this purpose without in- 
jury to plants. The paper contains the results of extended ex- 
periments carried on under my direction, by several of my 
assistants and particularly by Prof. W. 8. Barnard, Mr. Jos. 
Voyle of Gainesville, Fla., Mr. Clifford liichardson, assistant 
chemist of the Department of Agriculture, and Mr. II. G. Hub- 
bard, who has for over a year been devoting his time to practical 
tests in orange groves at Crescent City, Fla. 
Passing over the ordinary methods of oil emulsions by phos- 
phates, lactophosphates and hypophosphites of lime and various 
mucilaginous substances, experience shows that, for the ordinary 
practical purposes of the farmer and fruit-grower, soap and milk 
are among the most available substances for the production of 
petroleum emulsions. 
Ordinary bar sonp scraped and rubbed into paste at the rate of 
20 parts soap, 10 parts water, 30 parts kerosene and 1 part of fir 
balsam, will make, when diluted with water, an emulsion stable 
enough for all practical purposes, as the slight cream which in 
time rises to the surface, or the flakiness that often follows is 
easily dissipated by a little shaking. Soap emulsions are, how- 
ever, less satisfactory and efficient than those made with milk. 
Emulsions with milk may be made of varying strength, but one of 
the most satisfactory proportions is 2 parts of refined kerosene to 
1 part of sour milk. This must be thoroughl}' churned (not 470 
INSKCTICIPKS : BY O. V. RILEY. 
merely shaken) until a butter is formed which is thoroughly stable 
and will keep indefinitely in closed vessels and may be diluted ad 
libitum with water when needed for use. The time required to 
bring the butter varies with the temperature and both soap and 
milk emulsions are facilitated by heating the ingredients. Ordi- 
nary condensed milk may also be used by thoroughly stirring and 
beating it in an equal or varying quantity of kerosene. 
The diluted emulsion when prepared for use should be finely 
sprayed upon the insects to be killed, its strength varying for 
different insects or plants and its effect enhanced when brought 
forcibly in contact with the insects. 
Of mucilaginous substances, that obtained from the root of 
Zamia integrifolia, a plant quite common in parts of Florida, and 
from the stems of which the Florida arrowroot is obtained, has 
proved useful as an emulsifier. 
These petroleum emulsions have been used with success by Dr. 
J. C. Neal, of Archer, Fla., against the Cotton Worm, without 
injury to the plant, but their chief value depends on their efficacy 
against the different scale-insects which affect Citrus plants. Ex- 
perience so far shows that such plants do not suffer from its 
judicious use, but that it must be applied with much more care to 
most deciduous fruit trees in order not to injure them. 
[Salem Press, July, 1883.]