483 



suburb of our second largest city. It draws its patients from 

 all parts of the State, but more than a third of them come from 

 Chicago or its immediate neighbourhood. Three other asylums, 

 containing 30 per cent, more of our pellagrins, receive between 

 63 and 100 per cent, of their inmates from Chicago. The closest 

 relations of these especially pellagrous asylums thus seem to be 

 with our largest cities and not with our rural districts. These 

 facts would be more certainly significant, however, if pellagra 

 had been longer known and more thoroughly studied throughout 

 our territory, and if we had complete and reliable statistics from 

 the State at large. 



Simulium is said in Italy not to live in towns or to enter 

 houses ; but in the town of Havana, a village of 3,600 inhabitants, 

 situated on the Illinois River near the central part of my State, 

 it is so great a pest in spring that the people screen their windows 

 to protect themselves from the bites of the black-flics ; and we 

 have seen these insects collecting there in great numbers on the 

 inside surfaces of the window-panes of public rooms, such as the 

 offices of hotels. Furthermore, we have found biting species 

 of Simulium breeding and emerging in large numbers, not only 

 in the suburbs and outskirts of Chicago, but far within the 

 limits of that great city — in the Chicago River, which traverses 

 the city, passing through its most densely populated districts, 

 and also in drainage ditches beside the streets when these happen 

 to contain streams of running water for a sufficient time in spring. 

 Indeed, it is not too much to say that Simulium may breed in any 

 flowing stream within the city where the water is not offensively 

 foul with sewage and other contaminations. 



Reasoning from the time of the onset of pellagra in the case 

 of certain infants born in November and in December, when sand- 

 flies are not abroad in Italy, Dr. S.a.mbon comes to the con- 

 clusion that the incubation period in these cases could not have 

 exceeded three w(H^ks, this being the interval to elapse between 

 the time when these intants were lirst carried out in sjiring to 

 the fields where they might have been bitten, and the date of 

 the appearance of the rash which was the first symptom of the 

 disease. If this reasoning is sound, and these infantile cases 

 are fair examples of the incubation period of pellagra, then I 

 am troubled to explain the occurrence in Illinois of two asylum 



