20 THE kntojiologist's record. 



Another curious fact with respect to the galls still awaits explana- 

 tion. Each gall-fly produces a gall peculiar to itself, always the same 

 for any one species, yet greatly differing from that made by any other 

 species even when the two species are very closely allied. How the 

 mere oviposition in the leaf or bud should cause such a different 

 growth when pierced by different species is a great mystery, of which 

 nothing certain appears to be known at present, the different explana- 

 tions which have been given from time to time being very far from 

 convincing. Anyone interested in this subject Avould do well to con- 

 sult Hermann Adler's book, Alti'matiwi (irnerations, translated and 

 edited by Charles R. Straton, Oxford Clarendon Press, 1894. I can- 

 not conclude Avithout acknowledging my obligations to ]\Ir. Claude 

 Morley for kindly looking out some of the references, and also for 

 drawing my attention to several interesting particulars which I had at 

 first omitted. 



The Lepidopterological Books of the Nineteenth Century. 



By LOUIS 15. PEOUT, F.E.S. 



Probably there is no other branch of entomology in which such 

 gigantic strides have been made during the past century as in the 

 study of the lepidoptera. From being the most superficial and least 

 scientific of all entomologists, the workers at this order have risen to 

 an admittedly high — indeed, some would affirm, to a premier position 

 as regards the comprehensiveness of their work and the importance of 

 their contributions towards the elucidation of general biological 

 and evolutionary problems. Of course it is not maintained that they 

 have had any monopoly in this respect ; on the contrary, one is struck 

 with the fact that the great majority of the students of the anatomy, 

 physiology, etc., of insects, have been specialists rather in these branches 

 of work than in any particular order ; by no stretch of imagination can 

 such a pioneer in anatomical investigation as George Newport be 

 claimed as a specialist in the lepidoptera, nor can it be forgotten that 

 Weismann's first important discoveries as to histolysis and histogenesis 

 were made in connection with diptera. Nevertheless, a survey of our 

 literature will perhaps show that lepidopterists have been more ready 

 than other entomologists to avail themselves of, and to follow up in 

 their own studies, the work which has been done in this direction. The 

 reasons are not far to seek. In the first place, the attractiveness of 

 the order and the consequently large army of its devotees have resulted 

 in a very rapid advance in the merely systematic and superficially 

 descriptive work, and have placed us in the position to attend to further 

 developments ; a mere list of the names of writers on the lepidoptera 

 during the century would fill more space than I have at command for 

 this entire article. In the second place, the comparative ease with 

 which lepidoptera can be reared ab orn has given exceptional facilities 

 for the study of the problems connected with ontogeny and its probable 

 elucidation of phylogeny and evolutionary relationships ; and it woiild 

 be a disgrace to us, indeed, if we had shown ourselves totally un- 

 willing to avail ourselves of such facilities. 



In order to judge of the position of lepidopterology at the com- 

 mencement of the nineteenth century, and so to estimate better the 

 progress made, it will be well to consider briefly what were the standard 



