420 SUMMARY OF CURRENT RESEAllCHES RELATING TO 



Plague epidemics do not, as a rule, arise when the mean tempera- 

 ture is above 80° F., for the reason that at such temperature it is quite 

 exceptional to find a sufficiently low saturation deficiency. When, how- 

 ever, a high temperature occurs with a low saturation deficiency, plague 

 epidemics do arise and maintain themselves. In Rangoon, where the 

 temperature, although above 80° F. for over nine months in every year, 

 is associated with an exceptionally low saturation deficiency, plague occurs 

 at all seasons of the year. The autumnal recrudescences of plague in 

 Bonibay are found associated with a mean temperature of over 80° F., 

 but with a low saturation deficiency of less than • 20 of an inch. 



Generally speaking, it may be said that there is a critical saturation 

 deficiency for each range of temperature. At 80° F. this critical satura- 

 tion deficiency appears to be of the order of " 30 of an inch. At lower 

 ranges of temperature a higher degree of deficiency is needed to suppress 

 the epidemic, while at higher temperatures a somewhat lower deficiency 

 will sufiSce. 



