GRAIN CONSERVATION 131 



thermos flasks, actually gave off large quantities 

 of carbon dioxide when supplied with the necessary 

 oxygen, was also proved by direct experiment, in 

 which it was found that 50 grammes of the wheat 

 gave off 121 milligrams of carbon dioxide in 24 

 hours. We shall return to this question later on. 



Here, then, we have experimental proof that 

 air-tight storage prevents heating even in grain 

 containing a high percentage of moisture very 

 considerably higher, of course, than would be per- 

 missible in actual practice. 



To the physiologist, of course, there is nothing 

 surprising in these results, he could have predicted 

 them all from purely a priori considerations. All 

 the damage to stored grain which we have been 

 considering is the result of vital processes connected 

 with the metabolism of the organisms concerned, 

 and such vital processes cannot go on without a 

 supply of oxygen gas. It is merely another form 

 of the time-honoured experiment of burning a candle 

 in a closed vessel; as soon as the oxygen is exhausted 

 the candle goes out. It is somewhat surprising, 

 however, to find that the secret has been known 

 so long by certain peoples who can have had little 

 if any idea of the scientific principles upon which 

 their practice is founded. I have already referred 

 to the native Indian method of storing grain 

 in air-tight pits. Much more remarkable is the 

 practice of certain Natal farmers, who store their 



