236 PROF. HUXLEY ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS. 



Tab. XXXIX. 



Aphis Pelargonii. 



Fig. 1. A. Nearly full-grown foetus, extracted from its investments, and somewhat unfolded: t. anus, 

 whence the alimentary canal is seen taking a curved S-like course to the mouth, b. Terminal 

 chamber of one of the pseudovarial caeca of this embryo. 



Fig. 2. The mouth of this embryo seen from below. The " labium" (vi') already appears as a large single 

 process bilobed at its free end. 



Fig. 3. Side view of the head of a similar embryo, showing the relative position of the different append- 

 ages and the course of the oesophagus. 



Fig. 4. A nearly full-grown foetus in its pseudovitelline membrane: i'. the pigment of the eye; s. rudi- 

 mentary siphons. 



Fig. 5. A partially diagrammatic figure of the wingless viviparous form ot Aphis Pelargonii. The Roman 

 numbers indicate the typical somites of the body and their appendages ; the other numbers 

 mark the abdominal somites, a. Anus; g. genital aperture; s. siphon. 



Tab. XL. 



Reproductive Organs of the oviparous Aphis [Vacuna dryophila). 



Fig. 1. The female organs entire. One ovarian caecum only is represented; and 1 have purposely selected 

 one of those, the ovarian glands in whose apical chamber are very similar, at first sight, to ova. 

 A. Anus ; B. vulva ; c. vagina ; d. oviducts ; e, p, g, h, i, k. chambers of the ovary ; L. ovarian 

 glands ; m. coUeterial glands ; n. spermatheca ; 7} 8. seventh and eighth abdominal sterna. 



Fig. 2. The three anterior chambers of an average ovarian caecum. Letters as before, with the addition 

 of — 0. germinal vesicle of the nascent ova in the terminal chamber (k) ; o'. germinal vesicle of 

 ovum in i ; and o". of ovum in h; p. epithelium ; q. cord-like secretion of ovarian gland, / ; 

 I', inner capsule of ovarian gland. 



Fig. 3. The end of another ovarian caecum, showing very distinctly the apparent continuity of the cord, 

 q, with the ovum in the third chamber. The granules of the viscid vitelline mass (which is 

 surrounded by no membrane) are so numerous as to hide the germinal vesicle. 



Fig. 4. A. Posterior extremity of the ovum unaltered : r. chorion ; s. tubercular elevation ; t. append- 

 age ; 2<. its gelatinous investment ; v. rod-like bodies imbedded therein ; t;'. the same more 

 magnified, b. Anterior end of the ovum after the action of potash ; y. papillary elevation ; 

 z. internal markings of the chorion (y) ; w. vitelline membrane ; x. vitellus. c. Posterior 

 extremity treated in the same way : s . micropyle? 



