116 PHYSIOLOGY AND NATIONAL NEEDS 



breed vast numbers of weevils in the laboratory, 

 under exceptionally favourable conditions, but do 

 these insects ever occur in sufficient numbers under 

 normal conditions of storage to render the problem 

 of their extermination really serious ? " This very 

 legitimate question can, without the slightest hesita- 

 tion, be answered in the affirmative. My colleagues 

 and I have examined a great many samples of 

 wheat from various parts of the world and found 

 a very large proportion of them to be '' weevilled " 

 to a greater or less extent. We have had a parcel 

 of badly infected wheat delivered at my laboratory 

 which dripped weevils as it was carried about — 

 this, however, had been specially selected for us. 

 On the other hand, many samples which are believed 

 to be free from weevils show on incubation that they 

 are really infected and weevils emerge from the 

 grains in the course of a few days or weeks. This is 

 a fruitful source of error which has to be guarded 

 against in experimental work. Weevilling often 

 becomes greatly intensified in the course of a sea 

 voyage, owing to the warmth and moisture encoun- 

 tered in the tropics, and the cargo on reaching this 

 country is sometimes in a deplorable condition. 



It is no easy matter to estimate the actual amount 

 of damage due to weevilling. Noel Paton, however, 

 in his Indian Wheat and Grain Elevators, published 

 in 1913, tells us that " one of the largest shippers 

 of Indian wheat has said that the average wastage 



