274 Miscellaneous. 



what may be the significance of these abnormal individuals of Aphis 

 aceris deprived of the faculty of reproduction. 



Applying to these insects my theory of the biological evolution of 

 the Aphides, this third phase must also be a pseudogyne, and by 

 following it patiently I could not but succeed in obtaining sexual indi- 

 viduals. This has been the case, but not so quickly as I expected. 



At first the Aphides, which resembled their progenitor, increased 

 in size normally ; in twenty days they produced broods of embryos 

 furnished with long hairs, exactly like those which I had obtained 

 in the preceding brood. The forms with leaflets, observed by the 

 entomologists of Paris and the north, were wanting here at Mont- 

 pellier, upon the maple that I observed. But after the end of 

 May or the first days of June, all the normal forms had disappeared, 

 and I had left only embryos collected in groups upon the leaves, as 

 figured by Reaumur in the third volume of his ' Memoires.' 



June, July, and August passed without my nurselings increasing 

 in size or moving; at the beginning of September the leaves began 

 to fall, which became troublesome in the pursuit of my observations. 

 Fortunately I observed that when the fallen leaf ceased to furnish 

 them with nourishment, my little animals were well able to quit it and 

 seek their fortune elsewhere. I profited by this observation to transfer 

 these embryos from a yellow to a green leaf, fastening with a pin the 

 withered leaf to the fresh one. In a few hours all my Aphides 

 were attached to tho latter. 



By this means I had the pleasure, on the 12th September, of 

 seeing the skin of these hairy embryos split and as;ain furnish me 

 with an Aphis of noimal form and of a uniform light yellow colour, 

 Avhich grew very quickly, and began, in the first days of October, 

 to produce young of different dimensions. Smaller and more elon- 

 gated than any of their predecessors, these insects, which were at 

 first green, but afterwards became blackish brown, ran over the 

 branches of the maple, and showed that I had before me the two 

 sexes, for the copulations were frequent, the same male evidently 

 fecundating several females. 



But this is not all. Pushing polymorphism to the extreme point, 

 1 saw among numerous apterous males some which were winged, 

 and just as we have seen the second phase composed of emigrant 

 pseudogynes partly winged and partly apterous, we witness here a 

 production of apterous males to fecundate the females upon the same 

 tree, and of winged males which can go to a distance in search of 

 females which have fallen down or the wind has carried away. 



Soon after copulation the female deposits her ova under the buds 

 or in the fissures of the bark of the maples ; they are at first light 

 yellow, but soon become bright shining black. These are the ova 

 which hatch in the spring and furnish the foundress pseudogyne of 

 the colony. — Comptes Eendus, November 10, 1884, p. 819. 



Urnatella gracilis. 

 Prof. Leidy remarked that Mr. E. Potts had given to him, in 



