168 



RAYMOND PEARL 



TABLE 2 

 Causes of death in control females. Data to February 1, 1916 



fairly frequently. Ordinarily it gives very little trouble. Oc- 

 casionally it will break out into an epidemic of greater or less 

 violence, always as a result of a relaxation of some routine sani- 

 taiy or hygienic measure. During the course of this alcohol 

 experiment we have passed through a particularly violent epi- 

 demic of the sort mentioned. This fact is reflected in the large 

 proportion of the deaths due to diphtheritic roup or some of its 

 complications. On account of this epidemic the total mortality 

 in the experiment must be regarded as abnormally high. The 

 remarkable thing is that during the 15 months covered in this 

 report, i.e., to February 1, 1916, not a single one of the treated 

 birds succumbed to this disease, though they were exactly as 

 much exposed to contagion as the controls. This is a surprising 

 result. It seems impossible that it can be due to any real in- 

 crease in resisting power in the alcoholic birds. A possible 

 explanation is that the daily inhalation treatment acts as a 

 disinfectant of the air passages, and the treated birds do not take 

 the disease because its germs are killed or greatly weakened be- 

 fore thay have an opportunity to get an effective foothold. It 



