128 PHYSIOLOGY AND NATIONAL NEEDS 



Thus it ii 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 



