128 PHYSIOLOGY AND NATIONAL NEEDS 



Thus it is evident that a very minute aperture 

 in a tin or other receptacle may be quite sufficient 

 to maintain a number of insects in a healthy con- 

 dition in the interior, and to give rise to the belief 

 in their independence of ventilation. 



We have here, if I may venture to say so, an 

 admirable illustration of the fundamental import- 

 ance of scientific accuracy. You must not assume 

 that a tin or other receptacle is hermetically sealed 

 until you have proved it to be so, or you may be 

 led to utterly erroneous conclusions. 



We may then take it as definitely established 

 that insects cannot continue to live in air-tight 

 receptacles, and from this point of view at any rate 

 the storage of grain in air-tight granaries is fully 

 justified on scientific grounds. I may also tell you 

 that our experiments have shown that the growth 

 of moulds is prevented in exactly the same way ; 

 for if two jars of wheat are taken, each kept moist 

 by a supply of water in an inner tube, and one be 

 sealed and the other ventilated, both being kept in 

 a warm incubator, the wheat in the ventilated jar 

 will become mouldy in the course of a few weeks 

 while that in the sealed jar will not. 



We come next to the important question — ^What 

 is the effect of air-tight storage upon the phenomenon 

 known as " heating " ? It might very naturally be 

 supposed, from the care which has to be taken to 

 prevent this process from taking place under existing 



