68 Dr. Burnett on the Development of Viviparous Aphides. 
hand, they are, at first, simple collections, in oval masses, of nu- 
cleated cells. en again, they receive no special fecundating 
power from the male, as is the necessary preliminary condition of 
all true eggs; and, furthermore, the appearance of the new indi- 
vidual is not preceded by the phenomena of segmentation, as 
also is the case with all true eggs. Therefore their primitive 
formation, their development, and the preparatory changes they 
undergo for the evolution of the new individual, are all different 
from those of real ova. 
2, 
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Sacer, bay) 
EEG 
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EXPLANATION OF FIGURES, 
Figs. 1, 2,3 and 4, represent the egg-like buds in different stages of development—and 
as they are successively formed sprouting off from the internal surface of the parent. 
Fig. 1,a, shows a bud consisting of a single cell and situated between two larger. The 
same is true of 
Fig. 4, a, where, however, new cells are about to be developed around the central one. 
Fig. 3, a, shows the formation of a new bud by a constriction process, 
Fig. 2,4. appearance of the vitellus-looking mass near one extremity of bud. 
i Farther ps 0 t and diff te banal ga agg ee cut 
. 6. velopment an ‘ L 
es anne Pp erent parts appearing. a, represen 
* Milne Edwards thinks he has found true ova and ovaries in the viviparous forms 
of these animals. (Quoted by Dr. Carpenter in Brit. and For. Med. Chir. Rev., 1849 
iv, p.443.) I think he must have been deceived, as I was at first, by the ge ap- 
aeorey te carefully examined, closely resemble those of true oviparous 
vii 
if 
z 
