182 Dr. T. A. Chapman on the 



the body of the moth no longer as a second line of defence, 

 but as a store of food to be kept from enemies gross or 

 bacterial, from drying up, and from other dangers. The 

 precautions for the moth getting safely back into the 

 pupa-case, apparently rather a hopeless matter considering 

 its maggot-like structure, become more obviously matters 

 of necessity, leading up to the organic connection the moth 

 has with the pupa-case at the sites of the atrophied legs. 

 The brief time the moth remains out of the pupa-case, less 

 probably sometimes than five minutes, is not only import- 

 ant as minimizing the period of exposure to enemies, but 

 also as a period of deterioration of the moth as a food 

 material. 



We next come to the extraordinary structure (or want 

 of structure) of the moth itself. Everything aims at the 

 whole available forces and materials possessed by the larva 

 when it spins its cocoon being devoted to egg formation on 

 one hand and larval food on the other, and further that the 

 last object hardly takes a second place. If we compare 

 the iemale Heterogynis with those females of the Psychids 

 in which the structures have most degenerated, we find 

 that in the Psychids everything has given way to egg 

 development. The protection of the eggs is achieved 

 chiefly by mixing them with the hairs from the maternal 

 surface, and the female drops out of the case after she has 

 laid her eggs as a mere sciap of chitin, with considerable 

 masses of urate sand some little fluid. There is, in fact, 

 nothing whatever edible. In Heterogynis no hairs are 

 used to protect the eggs, and not only is the % devoid of 

 hairs and scales, but the cuticle is a simple membrane 

 without traces of the bases of hairs or scales, without any 

 skin points or other structures, and if I said actually 

 without chitin, I think I should commit no large error 

 demonstrable in a chemical balance. In the next place, 

 the urates are very small in amount. The quantity which 

 most insects void on emerging from the pupa is very 

 considerable, partly left in the pupa-case, partly voided 

 after the wings are expanded ; it is usually in solid 

 particles suspended in fluid ; there is usually some excess 

 fluid to be got rid of after the wings are expanded. Why 

 are these urates less in the case of Heterogynis ? If I am 

 asked are they really so, I must admit that I am not 

 prepared to meet the question, as having weighed the 

 material in question. But the thing seems to me to be 



