THE PLAGUE 125 



tion. In the transmission of the plague from rats to man by the flea 

 there is a time of variable length during which the flea is on neither 

 rat nor man. The duration and conditions of this interval are widely 

 variable and not equally favorable to the transmission of the disease. 

 In a hot, dry climate rat fleas soon die when detached from their hosts. 

 Local conditions may play an important role in the transfer of the 

 infected flea from rat to man. 



I think that it must be admitted that the evidence in favor of the 

 possibility of the transfer of the plague from rat to man through the 

 flea is strongly positive. Whether this is accomplished through other 

 agencies or not is an open question. 



