T. H. Huxley on the Phenomena of Gemmation. 207 
Thus Kyber bred the viviparous Aphis Dianthi and Aphis 
Rose for three years in interrupted succession; and the males 
and true oviparous females of the A. dianthi have never yet been 
with. The current notion that there is a fixed number of 
broods # nine or eleven,” is based on a mistake. 
under moderately favorable conditions, an Aphis comes to 
se in about a fortnight; and as each Aphis is known to be 
capable of producing a hundred young, the number of the prog- 
eny which may eventually result from a single Aphis during the 
six or seven warm months of the year is easily calculated. M. 
Tougard’s estimate adopted, (and acknowledged) by Morren, and 
copied from him by others, gives the number of the tenth brood 
as one quintillion. Supposing the weight of each Aphis to be no 
more than ;,';;th of a grain, the mass of living matter in this 
te would “exceed that in the most thick] y sce countries 
in t orld. 
pero Aphides, whether eae or wingless; but ordinarily, 
on the approach of cold weather, or even during warm weather, 
if the aipepliek of food fall short, the viviparous Aphides produce 
form ich are no ge oe viviparous, but are males = 
Seen: females, The former are sometimes winged, so 
times w — vee e later, with. a single doubtful comes 
nt differing from it, as Von 
old was ie The to eo re the Sudneb of what are termed 
