^^8 Pmhe [August 



information bearing directly on the question. As the majority of 

 the domesticated animals may harbor fleas of various species we 

 find that in 1909-10 out of 328 families where the disease was re- 

 ported, there were no animals present in 131 cases, that there were 

 animals present in 197 cases and that 125 animals had sickness or 

 death in 70 of the families. In this instance there were animals 

 present in 60 per cent, of the families. Again in a later report we 

 find that "out of 186 families in which acute epidemic poliomyelitis 

 occurred, 34 homes had illness, paralysis or death in 82 animals. 

 One hundred and ten of the families above mentioned had animals; 

 therefore, about thirty per cent, of 110 families with animals, had 

 paralysis or death in their animals." All animals in this case ex- 

 cept two may bear fleas. Again, out of 33 cases, all of which had 

 animals present, there were 28 cats and dogs in the home. It was 

 also reported that out of 328 families where vermin, insects, rodents, 

 etc., were present, there were 224 with rodents, which are common 

 hosts of fleas. 



Method of Raising Fleas. 



The adult fleas after each combing were brought to the labora- 

 tory and various trials were made to keep them ali^'e but under 

 no condition, moist or dry, did they live after five days. As this 

 would not do for obtaining material for experimental purposes 

 two cats infested with fleas were secured and these were kept in 

 the insectary until the last of May when they were placed out of 

 doors. Their bed consisted of several layers of newspapers which 

 were shaken every few days into a dish, and thus from fifty to 

 one hundred eggs were obtained each time. 



The following method proved most successful in raising fleas 

 from the eggs. The eggs with the debris, etc., from the beds, 

 were put in Petri dishes and these placed on the stage in small 

 moistening jars, one-third full of water (Plate X). The cover was 

 put on the jar and the whole apparatus placed out of the direct 

 light in the laboratory at ordinary room temperature. On excep- 

 tionally warm days the jar was partly opened to prevent the con- 

 densation of moisture in the jar from drowning the larvse. A little 

 floor sweepings from a vacuum cleaner and sometimes a little dried 

 blood were added to the culture. The larvae seemed to prefer the 

 dust and their own molt skins to the dried blood. By this method 



