STUDIES ON FERMENTATION. 197 



has certain generic and specific peculiarities which it shares with 

 the neighbouring cells ; but over and above this, certain peculiar 

 characteristics which distinguish it, and which it is capable of 

 transmitting to succeeding generations. If, therefore, we could 

 manage with some species of ferment to isolate the different 

 cells that compose it, and could cultivate each of these separatel}', 

 we should obtain as many specimens of ferments, which would, 

 probabl}^, be distinct from one another, inasmuch as each of 

 them would inherit the individual peculiarities of the cell from 

 which it originated. Our endeavours are directed to realizing 

 this result practically, by first thoroughly drying a ferment and 

 reducing it to fine powder. We have seen (Chap. III. § 6) that 

 this mode of experiment is practicable, that in a powder com- 

 posed of yeast and plaster the ferment preserves its faculty of 

 reproduction for a very long time. If we now drop a small 

 quantity of this powder from a sufficient height, and then, at a 

 certain distance below the cloud of dust so formed, open several 

 flasks previously deprived of air and containing a fermentable 

 liquid that has been boiled, immediately closing them all up 

 again, under such circumstances it is conceivable that some of 

 the cells of yeast diffused in the cloud of dust, and separated 

 widely in the act of falling, will enter some of our flasks singly, 

 and there develop an appreciable weight of ferment, all the 

 cells of which will have sprung from the same mother-cell. 

 We have proved that flasks may be easily impregnated under 

 these conditions, and our preliminary observations, although 

 incomplete, seem to favour the idea that numerous varieties of 

 ferment are to be obtained by these means. 



Spontaneous ferments, properly so called, of which we have 

 already spoken, are, after all, the result of sowings of this kind. 

 Originating in liquids which have been boiled, and then left to 

 themselves in contact with the air in a place where cells or 

 germs must have existed, these ferments must necessarily often 

 spring from single germs or from a limited few, and this also 

 would probably be a means of developing distinct varieties of 

 ferments. 



