96 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



vidual movements, but they do wave the first pair of legs when dis- 

 turbed. If a host comes within reach they are able to get on. 



Mr. Brain: In connection with this point I might mention that 

 in the case of Argas persicus Oken, the sense of smell seems to be 

 depended upon almost entirely in finding a host. Temperature 

 probably plays a slight part too, but I found by experiment that if 

 the first pair of legs are amputated the ticks live quite well for a time, 

 but apparently die later of starvation. A number of such ticks were 

 placed, together with normal specimens, in a box containing a chicken. 

 Next morning it was found that 27 out of 30 of the normal ticks had 

 fed while only 1 out of 30 of the specimens without the front pair of 

 legs was engorged. 



President W. D. Hunter: In that case are the legs not used for 

 grasping? 



Mr. Brain: I think not. The ticks use them most for touch. 

 The front pair are not used for grasping. 



Mr. E. C. Cotton : In regard to Mr. Hunter's question I think 

 that Dr. Nuttall, of the University of Cambridge, has demonstrated 

 very nicely that ticks are dependent upon the Haller's organ for the 

 location of their host. This organ which is olfactory in function, and 

 the only sense organ that has been clearly demonstrated in ticks, is 

 situated on the last tarsal segment of the first pair of legs. With 

 ticks of four different species, which in nature feed only upon blood, 

 he was able, by amputating this segment, thus removing the sense 

 of smell, to induce them to engorge on various liquids some of which 

 caused the death of the tick. 



President W. D. Hunter: If there is no further discussion we 

 will proceed to the next paper by Mr. S. J. Hunter, on ''Pellagra and 

 the Sand-fly. " 



PELLAGRA AND THE SAND-FLY, II 



By S. J. Hunter, University of Kansas, Lawrence, Kaiis. 



At the Washington meeting last year an account of this work up 

 to that time was given, in which 1,282 live sand-flies were used in an 

 ■endeavor to produce experimentally Pellagra in guinea pigs and 

 monkeys. The work was resumed at the opening of spring this season 

 and covered three lines of investigations.^ 



I As last year this work has been carried on with the assistance of Mr. W. T. 

 Emery, one of my graduate students and the pathologic side has been conducted 

 in conjunction with Dean Crumbine and the School of Medicine. 



