SCHIZONEURlNiE. 87 



germination. In the animal world it is also much the 

 same, for the number of mature individuals amongst 

 fish, for instance, does not increase, notwithstanding 

 that the roes of the cod and herring contain thousands 

 of separate ova. Some of these ova are eagerly sought 

 for food by other fish ; and many of the rest, if 

 hatched, become only larger prey for other animals. 



The presence of a group of Aphides on a tree will 

 not therefore lead to a certain conclusion that they 

 were bred there, though the presumptive evidence is 

 strong. 



There appears to exist amongst some Aphidologists 

 a certain confusion as to the terms pupa, egg, and 

 embryo ; and yet from the constitution of these bodies 

 there is a clear distinction. I conceive that an ovum 

 is necessarily composed of a vitellus with a germinal 

 spot, and certain membranes, which after the fertiliza- 

 tion of the egg and segmentation of the yolk, develop 

 into the embryo. The embryo therefore must be 

 clearly separable from the body which has developed 

 it. A pupa (chrysalis), from its very name supposes 

 an already organised form, and it is applied almost 

 wholly to some metamorphic phase immediately pre- 

 ceding the imago or perfect state. The jDroduce of 

 the winged female cannot therefore be a pupa in this 

 sense; unless two generations succeed each other, both 

 of which must be winged. The young dropped by the 

 imago has already its organs more or less developed, 

 and, of course, it neither contains a vitellus nor egg 

 adjuncts. It has, on the contrary, a greater analogy 

 to a maggot or caterpillar, and thus, in a restricted 

 sense, I have styled it a larva. 



In many species of Aphidinge these larvge are born 

 with a delicate membrane which enshrouds the young 

 animal, and this with its shining, glairy, lubricating 

 surface, gives it an ovoid appearance, and as such has 

 doubtless deceived early authors. 



On this account I have not used the word Piqnfer or 

 Pujnfer emigrant employed by Lichtenstein. 



