39 



addition to the vagina of the oviparous copulating female 

 of a sperm-sac and mucus-glands. In denying the pre- 

 sence of ovaria in the larviparous Aphis it would seem that 

 Prof. Steenstrup had been biased by a predilection for the 

 metaphorical name ofAmme, which he applies to them, and 

 by an a-priori conclusion, which he thus enunciates, viz. 

 " that as in the more perfect females an ovary especially is 

 formed, so in the e nursing y individuals a much-developed 

 uterus is presented, in consequence of which, they, as in- 

 dividualized uteri, have assigned to them, as the object of 

 their existence, the performance of the functions of a ute- 

 rus" (p. 113.) And, no doubt, the relations of the larval 

 Aphis to the embryo developing within it are much more 

 truly uterine than mammary more maternal than nu- 

 tricial. 



Some of the progeny of the primary germ-cell in the 

 human species are discernible in the ovaria of the human 

 embryo, and may have laid the basis of such ovaria, since 

 the like unchanged progeny of the impregnated germ-cells 

 have undoubtedly constituted the ovaria in the larviparous 

 Aphis : only in the human embryo the spermatic virtue has 

 been so far exhausted in the scanty remnant of the remote 

 progeny of the primary cell, which remnant goes to form 

 the ovarian germinal vesicles, that the stimulus of a new 

 coitus is requisite to set on foot the developmental processes. 

 In the Aphis, on the contrary, the presence of such common 

 external stimuli as warmth, light and nutriment suffice to 

 call in action the latent remnant of the spermatic virtue, and 

 to produce such a multiplication of the derivative germ-cells 

 and nuclei, as serves not only for the formation of the tissues 

 of the embryo, but to spare ; and such unmetamorphosed 

 germ-masses are stored up in its ovaria with their inherited 

 spermatic powder, which, notwithstanding its reiterated sub- 

 division, is still capable of responding to the action of the 

 same external stimuli to which, as the exciting cause of the 

 procreative act, the entire animal owed its origin. Had 



