the Egg &c. in Encyrtus fuscicollis. 29 



its eggs in masses in the interior of the caterpillar of the 

 Hyponomeuta ; as for the epithelial tube, this, according to 

 our author, was derived from the amnions of the embryos, 

 separated secondarily from the latter and united end to end. 

 These conclusions, albeit legitimate enough in appearance, 

 are nevertheless completely at variance with the actual facts. 



I have observed the oviposition of Encyrtus fuscicollis : 

 now the insect deposits its eggs not in the month of May, 

 but in July, not many days after it is hatched ; more- 

 over, it is not in the caterpillar, but in the ova themselves 

 of the Hyponomeuta that its eggs are laid. The little 

 Chalcid alights on a batch of eggs and remains there 

 for hours, piercing in succession with its ovipositor all or 

 almost all the eggs of which the batch is composed. I 

 reserve for a subsequent paper the details of this operation, 

 which I have watched for a long period, and content myself 

 with stating that the time necessary for the Encyrtus to 

 deposit its egg in that of the Hyponomeuta varies between 

 half a minute and two minutes ; almost immediately after- 

 wards it passes to another egg of the same batch, and so on 

 in succession for hours at a time ; then, when it has finished, 

 it makes its way to another batch, and recommences its 

 proceedings. 



One capital fact results from the foregoing observation. 

 Given the limited quantity of eggs contained in the ovaries 

 of an Encyrtus, it is materially impossible, in the short time 

 necessary for the process of oviposition, for it to deposit, 

 in each egg of the moth, a number of eggs equal to that 

 of the embryos composing one of the chains of which we 

 have spoken. A single egg must therefore be laid in the 

 egg of the Hyponomeuta, and this solitary egg must dissociate 

 itself into a large number of embryos. 



This conclusion, which forces itself upon us, is proved by 

 direct observation. I have witnessed the commencement of 

 the development of the egg, and have found that its amnion 

 is at first constituted like that of the other known Chalcids ; 

 afterwards, with the rapid multiplication of its cells, it elon- 

 gates in such a way as to form the epithelial tube. As for 

 the cells lying within the amnion, instead of going to form a 

 single embryo, as is usually the case, they become dissociated 

 in such a way as to give rise to a whole legion of little 

 morulce, which later on will become organized into embryos 

 and will arrange themselves in file, in proportion as the 

 amniotic envelope, increasing in size, passes from the primi- 

 tive vesicular form into that of a long flexuous tube. The 

 entire product of the segmentation is not, however, devoted to 



