Fleas and Plague 147 



the possibility of it. The investigations have 

 shown that the flea is the most common agent in 

 transferring the disease from rat to rat or from rat 

 to man. This may be accomplished by the flea 

 transferring the bacilli directly from one host to an- 

 other on its proboscis, or they may be carried in the 

 alimentary canal of the flea and gain an entrance 

 into the skin through an abrasion of some kind 

 when the flea is crushed as it is biting, or when some 

 of the bacilli are left on the skin in the excreta of the 

 insect. 



RESULTS OF VERJBITSKl'S EXPERIMENTS 



A very important series of experiments bearing 

 directly on this subject was made in 1902 and 1903 

 by Dr. D. T. Verjbitski. The paper giving the 

 results of this work was not published in any 

 scientific journal until 1908 when the Advisory 

 Committee published it in one of their reports. 

 The experiments were so well planned and exe- 

 cuted and the results so definite that I think it is 

 worth while to give in full his summary of results. 

 The bugs referred to are bedbugs. 



" (1) All fleas and bugs which have sucked the blood 

 of animals dying from plague contain plague microbes. 



"(2) Fleas and bugs which have sucked the blood 

 of animals which are suffering from plague only con- 



