380 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



have already stated it is extremely difficult if not impossible to account 

 for their development from the true sperm filaments of the male, and a 

 possibly more important objection to this theory of mine is, that the oval 

 bodies are found of perfect form in the females soon after the first ap- 

 pearance of the males, and before there could possibly have been any de- 

 velopment from the spermatozoa. The true mode of the fertilization of 

 the egg in this species is still open for discovery. The following facts 

 may be of use in the investigation : First, the eggs while still in the 

 ovaries are often seen to contain embryos in an advanced state of devel- 

 opment, and if the polar gatherings are an indication of segmentation 

 the fertilization must have taken place before the egg has left the ovi- 

 capsule ; Second, a careful study of a large number of females has failed 

 to reveal any other bodies in the ovaries than those mentioned; Thirds 

 I have never seen a filamentary spermatozoon anywhere in a female, 

 except in the spermatheca ; Fourth, There are never in the spermatheca 

 a sufiicient number of spermatozoa to fertilize more than a very small 

 fraction of the entire number of eggs laid and producing young ; Fifth, 

 the number of spermatozoa remaining in the spermatheca after the eggs 

 are nearly all laid is less than in the fall, showing that some have been 

 used, but a fair proportion remain unused ; Sixth, each sperm filament 

 of the male is longer than the entire egg and of such a size as not easily 

 to escape detection ; Seventh, the shape of the vagina is such that an 

 egg could be fertilized while on its passage out; Seventh, in Lecanium 

 hesperidum, of which no male has ever been found, the development of 

 the egg is almost exactly the same as in this Pulvinaria, except the 

 number of ova is much less, and they are developed in broods, so that 

 all the stages can not be seen at once, and the embryos are fully devel- 

 oped and the eggs hatched while still in the ovaries, thus showing that 

 the eggs in that species are fertilized, if at all, while still in the ovaries. 

 Should it be that a part only of tlie eggs are fertilized by spermatozoa, 

 it may be that these produce one sex while those unfertilized produce 

 the other, the latter most probably females. It would be an interesting 

 experiment to carefully separate a colony of females until after the 

 males had disappeared, this I have not been able to accomplish as yet. 



THE LAYING OF THE EGG. 



The egg havini,' escaped from its capsule into the general cavity of the 

 ovary, is now crowded by its fellow eggs into the oviduct, and thence 

 into the vagina and through the vulva and oviduct into the egg nest. 

 While in the ovary the shell appears perfectly smooth, but in its passage 

 through the vagina it probably becomes coated with a viscid substance 

 secreted by the vaginal glands, wliich causes the fine dust-like rings 

 secreted by the abdominal pores to adliere to the surface, giving an or- 

 namented appearance to the egg shell. Tlie egg now takes its place 

 with the other eggs in the egg nest. It thus appears tliat the egg laying 

 is almost entirely accomplished by the involuntary crowding of the de- 

 veloping eggs, and hence when the eggs are few in number, as in L, 

 hesperidum, they are not laid at all, but remain in the ovary until hatched. 



