February, '12] HUNTER: SAND-FLY AND PELLAGRA 61 



sulphite may be used to advantage in place of potassium bromide with 

 some makes of photographic plates, if one desires especially contrasty 

 results without the loss of fairly good detail. If this is used with care 

 the results obtained will be similar, although the temperature of the 

 developing solutions may be varied considerably and any one who has 

 ever developed photographic plates in warm weather will appreciate 

 it as a preventive of chemical fog. 



I have used a single arc light, with condensers, for illuminating 

 subjects on dark days. It is one of the very best sources for artificial 

 lighting when properly diffused and controlled, I find, too, that the 

 ground glass on a micrograph camera, must be ground very fine and 

 more luminous images are obtained if it is coated with a very thin 

 film of vaseline on the ground side. The advantage of this becomes 

 apparent when using the magnifier to assist in focusing. 



Backgrounds are seldom satisfactory, and, after much experiment- 

 ing with more than thirty different colors, or shades of colors, I found 

 that neutral gray gave the best results in most cases. Black or white 

 may be used under plate glass, but with black, undesirable reflections are 

 often encountered in the negative. White or opal glass is often much 

 superior to white paper for a background and does away with un- 

 pleasant shadows. 



I would like to pass around for the inspection of Association members 

 some illustrations of insects in natural colors: these photos are produced 

 by a method entirely different from the usual one. I want you to ob- 

 serve the richness and the truthful rendition of the colors obtained by 

 this process. This is the work of our Station Photographer Mr. Wil- 

 liam P. Beeching, Jr., and is a secret method, which he has not seen 

 fit to divulge. I think he is wise in not doing so, especially as the 

 process is not patented. 



President F. L. Washburn : Any further remarks on this paper? 

 The next paper on the programme is by S. J. Hunter, on "Pellagra and 

 the Sand-Fly." 



THE SAND-FLY AND PELLAGRA 



(Abstract^) 

 S. J. HtTNTER, University of Kansas 



For more than two hundred years the etiology of the human 

 disease, Pellagra, has been a subject of serious inquiry. Briefly, it 

 may be said that the causation of Pellagra is purely conjectural. The 



iThe complete paper is in the Journal of American Medical Association, Feb. 24. 



