132 PHYSIOLOGY AND NATIONAL NEEDS 



maize in large tanks of corrugated iron, in which 

 they burn candles until the air is exhausted before 

 closing them up, for the express purpose of prevent- 

 ing weevilling. 



Although it may seem safe to conclude, from the 

 evidence which I have already placed before you, 

 that the immunity of the grain in air-tight recep- 

 tacles from damage of various kinds is due to the 

 gradual replacement of the oxygen in the air by 

 carbonic acid gas, it was thought desirable to obtain 

 more exact information as to what really takes place 

 under these conditions. For this purpose a large 

 number of analyses of the gases present in the sealed 

 flasks, and a number of experiments on the effects 

 of various gases and mixtures of gases upon the 

 live insects have been made in my laboratory by 

 Mr. Elkington. These experiments are not yet 

 concluded, but I may place before you some of 

 the preliminary results. 



In the first place it is easy to demonstrate that 

 ordinary clean commercial wheat, at ordinary tem- 

 peratures, may give off considerable quantities of 

 carbonic acid gas. For example — two lots, each 

 weighing 300 grammes, of English wheat, having 

 a natural moisture content of 15*9 per cent, were 

 sealed up in two glass flasks for three months, the 

 receptacles being nearly full. The experiment lasted 

 from July 16th to October 17th, the flasks being 

 kept at ordinary room temperature. At the close 



