THE POLYSCOPIC CELL. A NEW MICROSCOPICAL 

 ACCESSORY. 



By Chakles S. Banks. 



{From the Entomological Section, Biological Laboratory, Bureau of Science, 

 3[anila, P. I.) 



For many 3'ears I have foiTnd myself handicapped in the study of the 

 anatomy of microscopic animals, especially insects, by having no means 

 whereby parts might be mounted either temporarily or permanently in 

 such manner as to obviate their distortion and at the same time to enable 

 the observer to view them from all sides. Those who have had to study 

 mouth parts, thoracic sclerites and genitalia of minute Coleoptera, Hy- 

 menoptera, Lepidoptera and Diptera, will appreciate what I mean when 

 I say that it is next to impossible to get, for example, the proper relation- 

 ships of the parts of male genitalia in Culicidae in preparations mounted 

 according to the ordinary models operandi. 



One needs but to take up any of the more recent publications dealing 

 with mosquitoes in which photomicrographs of the genitalia appear, to 

 be struck immediately by the very unsatisfactory appearance of most of 

 these, owing to displacement of parts, due to pressure of the cover glass 

 in making the fireparations. 



Furthermore, everyone who has observed the genitalia in living mos- 

 quitoes and those recently dead knows that the parts lie in many planes 

 and that no satisfactory idea of their relationships can be secured from 

 a slide which gives only a ventral or a dorsal aspect. It is true that by 

 using a ''built-up" cell, this distortion of parts may, to a certain extent, 

 be overcome, but at best it is exceedingly difficult so to mount one of 

 these preparations by ordinary methods as to get a lateral view; and 

 then, if one should succeed in thus mounting the specimen, he must 

 either jsrepare a second mount showing the dorsal surface and a third 

 one showing the ventral surface, or else reverse the slide, which is not 

 always feasible because of its thickness or of the position of the cover glass. 



After having tried every one of the classical cells, as well as numerous 

 others devised by myself, I have at last, I believe, secured a celL which 

 will prove useful not only to the entomologist but likewise to the general 

 biologist. 



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