Localities in which Pellagra is Prevalent. 11 



cases that have been sent to the Asylum. To my surprise 

 they have been found to come from widely scattered counties 

 of Eastern Kentucky, extending from the mountains to the 

 Ohio River. Judged by the distribution of these cases there 

 is no county in the Eastern third of the State that can be 

 regarded as exempt. And considering other cases occurring 

 in other parts of Kentucky, together with those recorded 

 from Tennessee, Illinois, Michigan and other states, it ap- 

 pears that pellagra may occur anywhere within our borders. 

 Yet it must be remembered that the history of these 

 cases at asylums is not fully known. People attacked by a 

 lingering malady sometimes become restive and dissatisfied 

 because of their ill health, and move away from the locality 

 where the disease was contracted. The cases scattered 

 about Kentucky may thus in some instances have come 

 originally from the mountains. I sometimes found on ques- 

 tioning patients about Corbin and Pineville that they had 

 somewhat recently changed their residences. 



Once introduced into a locality, however, the disease 

 appears to spread, as if some agent of infection were every- 

 where at hand. In some asylums, numbers of cases are 

 said to have developed after the admission of a single one. 

 And it may be remarked in passing that the fact, if fact it 

 is, that cases may originate within the walls of an asylum 

 is' opposed to the theory that Simulium is the agent of trans- 

 mission, for these insects are pre-eminently creatures of the 

 wild wood. 



THE INSECTS FOUND IN THE STREAMS. 



Most of the aquatic species collected in situations ex- 

 amined for Simulium were such as are constructed for living 

 in swift currents. They are in some cases quick strong 

 swimmers, but more often are of the lurking sorts that 

 depend upon clinging tightly to rocks and other objects in 

 the water. Species belonging to eight different orders were 

 collected by me, representing over forty species. 



