FERMENTATION AND DISEASE. 133 



suspended in a liquid. Thus knowledge rested until 1835, when Ca- 

 gniard de la Tour in France, and Schwann in Germany, independently, 

 but animated by a common thought, turned microscopes of improved 

 definition and heightened powers upon yeast, and found it budding 

 and sprouting before their eyes. The augmentation of the yeast al- 

 luded to above was thus proved to arise from the growth of a minute 

 plant, now called Torula (or Saccharomyces) cerevisice. Spontane- 

 ous generation is therefore out of the question. The brewer deliber- 

 ately sows the yeast-plant, which grows and multiplies in the wort as 

 its proper soil. This discovery marks an epoch in the history of fer- 

 mentation. 



But where did the brewer find his yeast ? The reply to this ques- 

 tion is similar to that which must be given if the brewer were asked 

 where he fonnd his barley. He has received the seeds of both of them 

 from preceding generations. Could we connect without solution of 

 continuity the present with the past, we should probably be able to 

 trace back the yeast employed by my Mend Sir Fowell Buxton to- 

 day to that employed by some Egyptian brewer two thousand years 

 ago. But you may urge that there must have been a time when the 

 first yeast-cell was generated. Granted exactly as there was a time 

 when the first barley-corn was generated. Let not the delusion lay 

 hold of you, that a living thing is easily generated, because it is 

 small. Both the yeast-plant and the barley-plant lose themselves in 

 the dim twilight of antiquity, and in this our day there is no more 

 proof of the spontaneous generation of the one than there is of the 

 spontaneous generation of the other. 



I stated a moment ago that the fermentation of grape-juice was 

 spontaneous ; but I was careful to add, " in what sense spontaneous 

 will appear more clearly by-and-by." Now, this is the sense meant : 

 The wine-maker does not, like the brewer and distiller, deliberately 

 introduce either yeast, or any equivalent of yeast, into his vats ; he 

 does not consciously sow in them any plant, or the germ of any plant ; 

 indeed, he has been hitherto in ignorance whether plants or germs of 

 any kind have had anything to do with his operations. Still, when 

 the fermented grape-juice is examined, the living Torula concerned in 

 alcoholic fermentation never fails to make its appearance. How is 

 this ? If no living germ has been introduced into the wine-vat, 

 whence comes the life so invariably developed there ? 



You may be disposed to reply, with Turpin and others, that, in vir- 

 tue of its own inherent powers, the grape-juice, when brought into con- 

 tact with the vivifying atmospheric oxygen, runs spontaneously and 

 of its own accord into these low forms of life. I have not the slight- 

 est objection to this explanation, provided proper evidence can be ad- 

 duced m support of it. But the evidence adduced in its favor, as far 

 as I am acquainted with it, snaps asunder under the least strain of 

 scientific criticism. It is, as far as I can see, the evidence of men 



