1918.] The Fifth Indian Science Congress. Ixxxvii 
The remaining close association, that whereby an increase 
of population produces an increase of fever, is now put before 
you. t is so directly opposed to widely accepted medical 
ideas that for some months I did not treat it seriously. But 
on my informing Major McKendrick of Kasauli of it he urged 
me not to reject it lightly, and drew my attention to some 
analyses of his which would suggest an explanation. I have 
therefore examined the corresponding relationship for all the 
ten provinces of India for which sufficient data are available, 
and have only found a single negative coefficient. The average 
value is+0°5. For those of you who are interested in sanitary 
matters I may briefly explain that the spread of malaria among 
men depends on the meeting of healthy men with infected 
mosquitoes, and the spread among mosquitoes on the encoun- 
ters between infected men and healthy mosquitoes ; hence the 
relations are symmetrical from the mathematical if not the 
esthetic standpoint, and an increase in the number of men has 
essentially the same bad effect as an increase in the number of 
mosquitoes. 
The conditions in the drier regions of India are so different 
from those of Bengal that it would clearly be dangerous to 
argue from one to the other; and this year’s malaria has drawn 
attention to the work of Major Christopher’s seven years ago. 
He then published data for malaria in the Punjab as affected 
by prices and rainfall, noting that malaria went up with excess 
of rain or a rise of cost of wheat in the same year, and with 
& defect of rain in the previous year. His work was most 
important though he did not separate the direct from the 
veal effects, and his numerical results and mine differ some- : 
what. 
Taking his data without modification I have worked out 
the table which is put on the screen. 
Correlation coefficients. 
eae 
| Rainfall | Rainfall Prices 
Fever — same previous same 
: year bined OR Siam 
Fever mortality | 4100 | +055 | —030 | + 0-45 
Rainfall, same year ay | + 055 + 1:00 | — 0-05 | +010 
Rainfall, Previous year .. — 0°30 — 0°05 IT 0-40 
Price of wheat, Same year | + 0°45 + 0:10 — 0:40 or 1:00 
0 ee eee : CSE GI ES cea ses pee 
| See Fig. XI. 
