210 PROF. HUXLEY ON THE AGAMIC REPRODUCTION 
The granular pseudovitellus takes no part whatever in the formation of the reproductive 
organs. In embryos of gj;th of an inch in length, I could very plainly observe a clear 
space with an endoplast in the middle of each of its spheroidal masses (Pl. XXXVIII, 
fig. 3). Similar masses constitute a larger or smaller proportion of the corpus adi- 
posum of the larva and adult insect; and I believe that the latter proceeds from the 
former. 
§ 5. Summary and Comparison of Germs and Ova. 
I will now sum up the results of the observations which have been detailed in the pre- 
ceding pages. 
1. The pseudovarium consists of vagina, oviduets, and pseudovarian cæca. 
2. The vagina is unprovided with either spermatheca or colleterial glands. 
3. The pseudovarian cæca are each divided into many chambers by constrictions. 
4. The apical chamber contains bodies which are not distinguishable from the germinal 
vesicles and spots of the true ovaria. 
5. These bodies, surrounded by a mass of clear substance representing a yelk, are set 
free as pseudova, and are then undistinguishable from true ova. 
6, The pseudova are eventually converted into cellular germs, apparently by the same 
process as that by which an ovum is converted into an embryo. 
7. In these germs the central part becomes a granular pseudovitellus, the peripheral 
a blastoderm ; the rudiments of the different organs next appear, and the germ becomes 
surrounded by a pseudovitelline membrane. 
8. Eventually the pseudovitellus probably becomes the corpus adiposum. 
9. All the other organs are developed from the blastoderm, which becomes distinguished 
into two layers. From the outer of these the muscles, nerves, limbs, and tegument are 
developed, while the inner gives rise to a part of the alimentary canal (?) and to the 
reproductive organs or pseudovarium of the larva. | 
10. The pseudovarium contains no particle of unchanged tissue of the germ, but is a 
considerably differentiated and readily distinguishable mass. The mass divides into ten 
lobes anteriorly; and these lobes become the pseudovarian cæca. Before the larva is 
horn, each cæcum is divided into three chambers, the two posterior of which contain rudi- - 
mentary embryos. 
11. The genital apparatus of the oviparous female consists of a vagina, oviducts, and 
ovarian ceca. The latter are multilocular; and the vagina is provided with the sperma- 
theca, and the two colleterial glands first demonstrated by Von Siebold. 
12. The rudiments of the ova are undistinguishable from those of the pseudova. They 
are developed in the lower part of the apical ovarian chamber, the upper part of which is 
occupied by the bodies I have termed ovarian glands. The ova are not at first enveloped 
in a chorion. 
13. In the lowest chamber the ova are provided with a chorion, vitelline membrane, and 
what appears to be a micropyle. 
If these propositions are correct, I see no valid objection to the conclusion, that the 
agamic offspring of Aphis is developed from a body of precisely the same character as that 
