60 



of the pistil (i). We have, in fact, at length f male (h) and 

 female (i) individuals/ preceded by reproductive individuals 

 (e, e) of a lower or arrested grade of organization, analogous 

 to the gemmiparous polypes of the zoophyte (e, e, fig. 2) 

 and the leaves (e, e, fig. 1) of the plant. 



I have described the process for its better intelligibility 

 in the Aphides as one of a simple succession of single in- 

 dividuals, but it is much more marvellous in nature. The 

 first-formed larva of early spring procreates not one but 

 eight larvae like itself in successive broods, and each of 

 these larvae repeats the process ; and it may be again re- 

 peated in the same geometrical ratio until a number which 

 figures only can indicate and language almost fails to ex- 

 press, is the result. The Aphides generated from virgin- 

 parents, by this process of internal gemmation, are as 

 countless as the leaves of a tree, to which they are so 

 closely analogous. 



It generally happens that the metamorphosis which I 

 have described as occurring after the seventh or eleventh 

 generation takes place much earlier in the case of some of 

 the thousands of individuals so propagated (k, fig. 3) : just 

 as a leaf-bud near the root may develope a leaf- stem, a 

 flower and seed-capsule (k, fig. I) with much fewer antece- 

 dent generations of leaves from buds than have preceded 

 the formation of the flower at the summit of the plant ; or 

 just as one of the lower and earlier formed digestive polypes 

 may push out a bud to be transformed into an ovarian sac 

 (k) and a generative medusa (/). The analogy is beautifully 

 and closely maintained throughout. 



The wingless larval Aphides are not very locomotive ; 

 they might have been attached to one another by continuity 

 of integument, and each have been fixed to suck the juices 



veloped in the oviparous female they soon fall. I have, however, retained 

 them in the diagram for the better illustration of the analogy. Many 

 of the virgin viviparous Aphides acquire wings, but never perfect the 

 generative organs. 



