AND MORPHOLOGY OF APHIS. 235 



consequence of the enlargement of the pseudovum {g), which is about ^^^th of an inch in 



diameter. 

 Fig. 3. The pseudovum is still more enlarged, and the second chamber is nearly distinct. The vesicle, 



ef, remains, and exhibits certain indistinct granules in its contents. The cells of the blasto- 

 derm of c measure about v-irxroth of an inch in diameter. 

 Fig. 4. The second chamber is quite distinct from the first, and contains a mass {ff) in which no clear 



vesicle could be discovered : this mass became clearer and irregularly areolate by the action of 



water. 

 Fig. 5. The cellular germ-mass. The cells or clear cavities have a diameter of about ^yjnjth of an inch ; 



their endoplasts are hardly more than roWuth of an inch in diameter. 



Tab. XXXVII. 

 Aphis Pelargonii. Letters as before. 



Fig. 1. A portion of the blastoderm and pseudovitellus of an unaltered germ, only y|-jth of an inch in 



length, but otherwise like the preceding. The clear vesicles measured jaVoth o( an inch ; the 



endoplasts , aiim th. 

 Fig. 2. A germ extracted from its chamber and treated with acetic acid. It has no pseudovitelline 



membrane. 

 Fig. 3 a. A germ extracted from its chamber. It is enclosed within a pseudovitelline membrane {k) ; and 



its pseudovitellus is arranged in obscure spheroids, of which one is represented in 3 b. acted on 



by water. Its granules are about ^Tnnrth of an inch in diameter. 

 Fig. 4. Germ ^xsth of an inch in length. The cells of the posterior end (3) present a sort of break [1), 



and the blastoderm on one side is greatly thickened. The thickened portion oifers an indication 



of a division (to). The anterior end (?/) is also somewhat thickened. 

 Fig. 5 a. Germ Tsirth of an inch, enclosed within its pseudovitelline membrane : n. rudiment of the 



abdomen ; o. of the thorax ; p. of the head ; V. gap corresponding with I, and now filled by the 



pseudovitellus ; q. inner layer of the germ ; r. that portion of it which will become the pseud- 



ovarium. 5 b. Diagrammatic view of the same, viewed from above. 

 Fig. 6. Lateral view of a larger germ without its pseudovitelline membrane. The anterior part of the 



cephalic blastoderm {p) has extended upwards, and constitutes the procephalic lobe^'. The 



rudiment of the pseudovarium (r) is still more distinct than in the preceding. 



Tab. XXXVIII. 

 Aphis Pelargonii. 



Fig. 1. Embryo enclosed within its pseudovitelline membrane. The pseudovitellus has aggregated over 

 the abdomen, and more or less completely left the thorax. Letters as before, except — *. the 

 first larval integument ; lb. labrum ; at. antenna ; iv'. mandible ; v'. first maxilla ; vi'. second 

 maxilla; vii'. first, viii'. second, and ix'. third thoracic leg. 1 a. The same embryo seen from 

 below. 



Fig. 2. Embryo of the same size, viewed from below and the side, the blastoderm unfolded, and the 

 appendages separated. 



Fig. 3. Highly magnified view of part of the pseudovitellus, and of the rudiment of the pseudovarium, 

 in an embryo ^oth of an inch in length. 



Fig. 4. Embryo -^\.\\ of an inch, enclosed in its pseudoviteUine membrane. 



Fig. 5. Embryo 7^*^ of an inch, in its pseudovarian chamber. 



VOL. XXII. 2 I 



