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well-known fact that many text-books on animal and vege- 

 table histology are illustrated by diagrams depicting details 

 of structure which it is safe to say could only be recognised 

 in the original tissue by the expert. On the other hand, 

 great though the advantages of photography over drawing 

 may be, in that the "personal element" is practically 

 eliminated, yet there is no doubt that in many cases a care- 

 fully prepared drawing is preferable for educational pur- 

 poses. The science of bacteriology owes much to photo- 

 micrography, for here the latter more than holds its own. 



To produce really good work the microscopist must be an 

 expert photographer. There are many who, although quite 

 familiar with the modern microscope and its manipulation, 

 fail when attempting photomicrography, solely by reason of 

 a want of practical experience in the purely photographic 

 portion of the work. 



Another important factor which will largely contribute to 

 success in the practice of this work is the necessity for 

 suitably preparing the specimen for photography. No lens 

 or method yet discovered will enable the operator to photo- 

 graph a dense chitinous insect section, and at the same time 

 to reproduce the finer details of structure. The same 

 remark will apply to the case of a badly stained preparation. 

 Whilst on the subject of the preparation of microscopical 

 specimens for photography, I might incidentally mention 

 that some method for preserving insects' eggs as permanent 

 specimens is badly needed, as is also some means of dis- 

 playing the neuration of wings, — such as, for example, by 

 infiltration or injection of some staining agent. 



The careful worker will proceed with and record his ob- 

 servations systematically. In this connection I would draw 

 attention to the value attaching to a series of photographic 

 representations of the life history of any particular insect. 

 There are immense numbers of these whose life history and 

 structure have never been accurately studied, and the ento- 

 mologist will find abundant material for investigation pro- 

 vided in the important changes undergone by insects during 

 the period of their development. The photographer should 

 be careful to represent allied structures as nearly as possible 

 at the same magnification, and I scarcely need to remind him 

 that his measurements should be taken on the metric system, 

 such terms as "Tines" being quite out of date. He should 

 also keep an indexed record of his work, giving every par- 

 ticular as to the conditions under which his results were ob- 

 tained. I would recommend the naturalist photographer, 



