Packard ] INSECTS OF THE PLANT HOUSE. 
105 
a mammary gland,” and he then compares these insects in 
this respect to the mammals. 
Now upon pressing the body of the Aphis, placed in a 
drop of water in the animalcule stage, we readily squeeze out 
the contents of the abdomen, including the ovaries. Instead 
of a numerous mass of eggs in various degrees of maturity, 
we are astonished to see a series of young Aphides, in va¬ 
rious stages of development. The creature brings forth its 
young alive. Moreover, the parent, as Bonnet observed, is 
a virgin. No males are in existence. The first brood hatch¬ 
ing out in the spring are all females. As soon as the leaves 
unfold the virgin rears its brood of } r oung; these in turn 
produce their spinster offspring, and the number of broods is 
only limited by the approach of frost. Finally, after from 
eight to ten broods, males and females appear ; the latter lay 
fertilized eggs, by which the species is represented during 
the winter. Such are the powers of multiplication of these 
Aphides that a spring-born virgin ma}’’ become the happy 
mother of a quintillion daughters and granddaughters. At 
least such is the belief of M. Fougard as quoted by Prof. 
Morren in his well known paper “Sur le Puceron du Pecher.” 
A certain species which Fougard calls “ Puceron lanigere” 
produces ten viviparous generations and one oviparous gen¬ 
eration. Each generation produces from ninety to one hun¬ 
dred and fifteen individuals, the mean of which is one 
hundred. He thus obtains the following table of genera¬ 
tions : — 
Generation. 
Produce. 
1st 
2il 
3d 
4th 
5th 
Cth 
7 th 
8th 
9th 
10th 
. . . . 1, Aphis, 
100, one hundred. 
. 10,000, ten thousand. 
1,000,000, one million. 
. . 100,000,000, hundred millions. 
. 10,000,000,000, ten billions. 
. 1,000,000,000,000, one trillion. 
100,000,000,000,000, hundred trillions. 
10 , 000 , 000 , 000 , 000 , 000 , ten quadrillions. 
1 , 000 , 000 , 000 , 000 , 000 , 000 , one quintillion. 
9 
