30 KANSAS UNIVERSITY QUARTERL\ . 



deaths have occurred in their counties during periods ranging from 

 six to thirteen years; and Clark, Ellis, Ford, Ness, Pratt, Stafford 

 and Stevens counties report a marked freedom from the disease. 

 Correspondents in some of the eastern counties, too, report that 

 very little diphtheria is known in their localities, but there is a 

 larger proportion of such answers from the western part of the 

 state. 



When we come to compare the conditions which surround these 

 different portions of the state, we find that the west, especially the 

 soutliwest, has the least rainfall; the elevation is greater there, and 

 in general there is better drainage. In the southern tier of coun- 

 ties the rainfall is probably as great as in the northern, and 

 evidently greater in the eastern seven than in the corresponding 

 counties of the northern tier. Density of population is certainly a 

 factor influencing the death rate in an infectious disease, and es- 

 pecially in one that is so often spread by crowded school-rooms; 

 and the sparsity of population, without doubt, partially explains 

 the freedom from diphtheria which seems to be enjoyed in the 

 western part of the state. The average density of population in 

 the seven eastern counties of the southern tier, however, is prob- 

 ably as great as that of the corresponding seven of the northern 

 tier; since the southern has about 58 per cent of the combined 

 school population of the fourteen counties averaged for the twelve 

 years, while the northern tier has 42 percent. This difference will 

 nearly make up for the greater area of the southern group. 



In this connection we will compare statistics of localities outside 

 of the state. In the city of Denver the average death rate of diph- 

 theria and croup during an eleven 5'ear period, 1886 to i8g6 inclu- 

 sive, is 93.45 per 100,000 annually. In Massachusetts during the 

 years 1876 to 1895 inclusive, the rate from diphtheria and croup 

 combined was 96.4 per 100,000, and for diphtheria alone it was 

 72.2. In Michigan during the ten years, 1885 to 1S94, the rate of 

 diphtheria alone was 46.88 per 100,000. In the District of Colum- 

 bia in the fourteen year period, 1884 to 1897, the rate of diphtheria 

 and croup among the white people averaged 52.5 per 100,000. So 

 we see that the death rate of diphtheria in Denver, where the ele- 

 vation is great and the rainfall and humidity low, is not much less 

 than that of Massachusetts, and exceeds that of the District of 

 Columbia. 



For further comparisons of state with state, I have only the 

 record of the one year ending May 31, 1890; but this is of some 

 value when we compare large groups of states. lu Grand Division 



