Precautions 321 



The work should be done by a calm, thoughtful and careful 

 person — ^best by one who has had some experience. 



Conspicuous notices of what has been done should be placed on 

 the doors, and the doors should be locked so that no one can stray 

 into the rooms. 



The gas is lighter than air, therefore one should always begin in the 

 rooms at the top of the house and work down. 



After fvimigation is over the contents of the jar should be emptied 

 into the sewer or some other safe place. The jars should be washed 

 thoroughly before they are used again. 



It must be remembered that cyanid is a deadly poison; but it is 

 very efficient against household insects, if carefully used, and is not 

 particularly dangerous when properly handled. 



LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY 



While this text was in press there came to hand an important paper 

 presenting a phase of the subject of black fly injury so different from 

 others heretofore given that we deem it expedient to reproduce here 

 the author's summary. The paper was published in The Journal 

 of Cutaneous Diseases, for November and December, 1914, under the 

 title of "A Clinical, Pathological and Experimental Study of the 

 Lesions Produced by the Bite of the Black Fly" (Simulium venus- 

 tum)," by Dr. John Hinchman Stokes, of the University of Michigan. 



Resume and Discussion of Experimental Findings 

 The principal positive restdt of the work has been the experimental 

 reproduction of the lesion produced by the black-fly in characteristic 

 histological detail by the use of preserved flies. The experimental 

 lesions not only reproduced the pathological pictures, but followed 

 a clinical course, which in local sjonptomatology especially, tallied 

 closely with that of the bite. This the writer interprets as satis- 

 factory evidence that the lesion is not produced by any living infec- 

 tive agent. The experiments performed do not identify the nature 

 of the toxic agent. " Tentatively they seem to bring out, however, 

 the following characteristics. 



1. The product of alcoholic extraction of flies do not contain 

 the toxic agent. 



2. The toxic agent is not inactivated by alcohol. 



3. The toxic agent is not destroyed by drying fixed flies. 



4. The toxic agent is not affected by glycerin, but is, if anything, 

 more active in pastes made from the ground fly and glycerin, than 

 in the ground flies as such. 



