52 ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS 
the ovarian tubes with the oviducts in all insects, is such as to render 
the negation of the term ‘ovary’ to those two bodies from which the 
slender extremities of the eight oviducal and uterine tubes proceed in 
the larval Aphis, to say the least, quite arbitrary. My examinations 
agree with those of Siebold, in determining scarcely any appreciable 
difference between the ovaria of the oviparous and those of the vivi- 
parous females. The contents of the ovarian tubes differ, inasmuch 
as they contain oval masses of granules or nuclei, comparable to the 
germ-mass in its state of minutest subdivision, in the virgin Aphides, 
and not ova with the germinal vesicle as in the oviparous females,” 
—Tlbid. p. 38. 
“The completion of an embryonic or larval form by the develop- 
ment of an ovarian germ-cell, or germ-mass, as in the Aphis, without 
the immediate reception of fresh spermatic force, has never been 
known to occur in any vertebrate animal. 
“The condition which renders this seemingly strange and mys- 
terious generation of an embryo without precedent coitus possible, is 
the retention of a portion of the germ-mass unchanged. One sees 
such portion of the germ-mass taken into the semitransparent body 
of the embryo Aphis, like the remnant of the yelk in the chick. I at 
first thought that it was about to be enclosed within the alimentary 
canal, but it is not so. As the embryo grows, it assumes the position 
of the ovarium, and becomes divided into oval masses and enclosed 
by the filamentary extremities of the eight oviducts..... "—Tbid. 
pp. 69-70. 
“It would be needless to multiply the illustrations of the essential 
condition of these phenomena. That condition is, the retention of 
certain of the progeny of the primary impregnated germ-cell, or, in 
other words, of the germ-mass unchanged, in the body of the first 
individual developed from that germ-mass, with so much of the 
spermatic force inherited by the retained germ-cells from the parent 
cell or germ-vesicle as suffices to set on foot and maintain the same 
series of formative actions as those which constituted the individual 
containing them.’—Jdzd. p. 72. 
“The physiologist congratulates himself with justice when he has 
been able to pass from cause to cause, until he arrives at the union 
of the spermatozoon with the germinal vesicle as the essential con- 
dition of development—a cause ready to operate when favourable 
circumstances concur, and without which cause these circumstances 
would have no effect. 
“What I have endeavoured to do has been to point out the con- 
ditions which bring about the presence of the same essential cause in 
