462 Dr. Filippi on the Generation of an Hymenopterous Insect. 



that the larger moiety of these ova was attacked by a parasite, 

 and that in the interior of this parasite another was developed, 

 which when fully grown transformed itself into a nymph within 

 the ovum of the Rkynchites, and at last gave birth to a little 

 Hymenopterous insect of the numerous family of the Ptero- 

 malidce ! 



Here is a summary of the facts. Among the ova which have 

 just been deposited by the Rhynchites upon leaves still fresh and 

 green, there are some which are altogether clear, and which when 

 examined by the microscope present no trace of embryonic cells. 

 Regarding them attentively, we observe at some points of the 

 ova a very small animalcule, like an infusorium, provided with a 

 tail which it m^oves briskly with a lashing motion ; but which 

 in form, and in the hairs which beset its body, resembles certain 

 Dipterous larvse (PI. XVI. A. fig. 1 & 2). In most cases there 

 is but a single one in each ovum, but I have also seen two and 

 even three. No organs can be distinguished in the interior of the 

 parasite under this form ; it is only later that a kind of vesicle 

 makes its appearance in it (fig. 3, 6) . Very soon the parasite loses 

 its mobility, and the internal vesicle, increasing in size, distends 

 the integument of the animal in which it is formed ; so that the tail 

 drawn in by this distension, ends by disappearing, and the body 

 of the first parasite becomes reduced to a mere sac (fig. 4, 5). 

 What I have called a vesicle becomes more and more developed, 

 presents first the outline of a head, and begins by its vermicular 

 motions to give signs of life (fig. 6). 



It is in fact the larva of one of the Pteromalida, which, when 

 it has arrived at its complete development, appears armed with 

 two delicate and elongated jaws, without any trace of legs, and 

 simply with a projecting crest on the sides of the body (fig. 7). 

 When this larva is going to pass into the nymph condition (which 

 takes place eight or ten days after its first appearance),- it changes 

 its skin — tears by this movement the envelope of the first parasite, 

 and spins a cocoon, in consequence of which the ovum of the 

 Rhynchites takes on a brov/n colour (fig. 8). Lastly, after another 

 delay of a week or so, the little Hymenopterous insect efi'ects an 

 opening in the ovum and makes its exit. 



I shall not at present give the figure and description of the 

 perfect insect, which perhaps belongs to a new genus, but instead, 

 I will rather ofi'er a few remarks upon the facts which I have just 

 detailed. The first question which I asked myself was, whether 

 this might not be the case of a parasite within a parasite, that is 

 to say, an ovum deposited by the Pteromalian female, in the body 

 of a Dipterous larva, which feeds on the ovum of a Rhynchites ; 

 but many circumstances have caused me to reject this interpre- 

 tation. I have examined about a hundred ova oi Rhynchites thus 

 attacked, and have always witnessed the series of metamorphoses 



