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these heaps, for it is conclusively shown that these stacks 

 are the homes and breeding-places of myriads of bacteria 

 in fact, a complete flora of fungus life is to be found within 

 them, for side by side with the bacteria are members from 

 many other parts of the great group of fungi of which the 

 microbe life is only a small section, At this time the condi- 

 tions of life are highly favourable to the welfare of this flora 

 and the growth and development of all its members begin 

 apace. And fermentation is the outward and visible sign of 

 the stirring of growth and increase within and its direct out- 

 come. For as the germs develop, food is a necessity to them 

 and they can only obtain it from their immediate environment, 

 hence they draw nourishment from the leaves comprising the 

 tobacco heap, working meanwhile subtle changes in them, 

 and, at the same time, inducing that little-understood pheno- 

 menon, heating. Why tobacco, hay, cotton, and other vege- 

 table matter should ' heat' under similar circumstances is 

 at present very vaguely explained. We know, however, one 

 fact about it : it is due to the agency of fungi (among which 

 we include the bacteria), for it has been clearly proved in the 

 case of cotton-waste, for instance, that if the vegetable mat- 

 ter be sterilised so that there is no possibility of germ inha- 

 bitants there is no heating ; introduce germ life, and at once, 

 given the presence^ of oxygen, we have heating. This is, 

 however, at present a phenomenon which presents almost a 

 clear field for research. But in the case of tobacco, heating 

 is carefully checked before it has gone very far by a continu- 

 ous turning of the stack inside out and 'sides into middle/ 

 no temperature higher than 90 degrees Fahr. being allowed/' 



