282 Mr. Newport on the Generation o/" Aphides. 



no fire, and where the temperature ranged from about 45° Fahr. to 50° Fahr. 

 In the second week of November, as the temperature of the season became 

 cooler, I first noticed several specimens with rudiments of wings, and a few days 

 afterwards these cast their skins and became fully developed. Most of these 

 individuals were males. At this time there were also a great many very young 

 specimens. On the 30th of November the number of winged individuals had 

 greatly increased ; there were many with only the rudiments of wings ; and 

 there was also a great abundance of black oval eggs distributed everywhere 

 on the young shoots of the plant, not only on the leaf-buds, but on the stems 

 of the leaves and branches. I saw an Aphis at that moment bearing two eggs 

 at the extremity of her body. On placing one of these beneath the microscope, 

 I was quickly assured of its real nature : it was not a capsule that included a 

 ready-formed embryo, but a true egg. When first deposited the egg is of an 

 orange-yellow colour, but it soon acquires a much darker hue, and ultimately 

 becomes of a deep shining black. The colour is entirely dependent on the 

 pigment of the shell, and is much darker in some specimens than in others. 

 The eggs are firmly glued to the plant, and are not easily removed. The egg 

 of the Aphis is similar to that of other insects : it is composed of an orange- 

 coloured yelk, formed of yellow nucleated cells, and surrounded by a very 

 slight quantity of transparent vitelline fluid. It contains also a very large 

 germinal vesicle with a distinct macula or nucleus. This vesicle is three or 

 four times as large as the cells that compose the yelk, and, unlike that of 

 most other impregnated eggs of insects, does not disappear until some time 

 after the egg is deposited. The vesicle is so persistent, that in one instance, 

 in which I examined an egg shortly after it came from the body of the Aphis, 

 it did not disappear for several seconds after the egg was crushed under the 

 microscope. 



Wishing to observe the deposition of more eggs, I selected four specimens 

 of the Aphis for experiment : two of these were males, which as yet were in 

 the pupa state, and had only the rudiments of wings ; the other two were 

 large apterous females ; these were placed on a detached branch of the rose, 

 inclosed in a stoppered glass vessel, and removed to an apartment, in which 

 the temperature ranged from 55° Fahr. to about 60° Fahr. On the 2nd of De- 

 cember, when the temperature of the air of the room was 58° Fahr., I was 



