166 BULLETIN OF THE 



1. Diarrhceal diseases are far more destructive to infants than to 

 adults. 



2. They prevail almost exclusively during the warmest months 

 of the year. 



3. They are more prevalent in the region of this country north 

 of the north line of the Gulf States and east of the Rocky Moun- 

 tains. 



The first two conclusions are universally admitted ; the third is 

 not so generally recognized. 



Tw# additional propositions are suggested : 



1. These diseases occur in groups, when the cases rapidly mul- 

 tiply during successive days for a week or fortnight, followed by an 

 interval during which few or no cases occur. 



2. These groups correspond with waves of continuous high tem- 

 perature during day and night, which spread, at shorter or longer 

 intervals during the summer months, over the northern climatic 

 belt of this country, lasting from three to fourteen days, and vary- 

 ing in intensity at different times and in different years. 



The first of these propositions cannot be established, because of 

 the absence of statistical data relating to the beginning of the 

 initial symptoms of the diseases ; the second is proven by data sup- 

 plied by the Signal Service Bureau. A comparison of these data 

 with the mortality statistics shows : 



1. That the month of July is the hottest and sickliest month of 

 the year, most conducive to bowel affections, and most fatal to 

 children under five years of age. 



2. The epidemics of bowel affections of children, incident to the 

 summer season, have their beginning nearly simultaneously with 

 the first exacerbation of heat, which usually occurs in the latter 

 half of June ; and the maximum daily mortalities more frequently 

 correspond with the maximum temperatures, which occur in periods 

 of three or more days, at longer or shorter intervals during the 

 snmmer months. 



3. With the usual lowering of temperature and absence of ex- 



