452 
POPULAR SCIENCE REVIEW. 
of the body. The male germs, also enveloped in a fine 
covering, are found on each side of the digestive tube included 
within the ovarial sheaths which have formed over the female 
ovules ; fine granular matter fills these tubes, which is of a 
vivid green colour. The male germinal vesicle, which has 
become a seminal reservoir, is a sac of considerable size, 
situated on the intestine. It is full of seminal corpuscles and 
coloured granules, and the vesicle terminates by a slender 
neck and duct leading to the ovarian tubes. The embryos of 
the viviparous Aphides contain, therefore, at the moment of 
their birth the new generations to be successively developed. 
The description of so many separate minute parts is neces- 
sarily complicated, and scarcely intelligible without diagrams ; 
but we have not ventured to construct them from the text. 
Insect larvae have hitherto always been supposed to produce 
but one perfect insect. But the Aphis “larva” must itself be now 
considered a perfect insect of hermaphrodite type if BalbianPs 
very careful dissections are confirmed. Every succeeding 
larva is therefore a creature generated and developed according 
to the received formula “ omne vivum ex ovo” 
Quite recently the asexual multiplication of the larva of a 
fly ( Gecidomyia ) has been noticed and described by Leuckart. 
The first discovery of this kind was made some years before 
by Prof. Wagner in Kasan. The examination of the facts 
relating to this discovery must, however, be reserved for a 
future occasion. 
