80 THE MICROSCOPE. 



tunity ? Whichever way they come, it would 

 be too sloiv a process to wait for the natural 

 appearance of these plants in the worts of the 

 brewer and distiller/' 1 The juice of the grape 

 propagates the seeds of the yeast with this won- 

 derful rapidity, " because it contains the food 

 which, in kind, in form, and in quantity, is best 

 suited to its rapid growth. . . . The minuteness 

 of the yeast-plant, consisting in its simplest 

 form of only a single cell, long prevented it from 

 being generally regarded as a form of living 

 matter. But the changes it undergoes in the 

 fermenting tub, day by day, as shown by the 

 Microscope, prove it to be unquestionably a 

 growing vegetable" 2 



8. In his Bridgewater Treatise, Dr. Prout 

 thus disposes of the theories we have been con- 

 sidering : " All hypotheses assumed to explain 

 organization by laws, whether by laws of matter, 

 or by what are called laius of development, must 

 be rejected. . . . We are drawn irresistibly to 

 the conclusion, that when a new and specific 

 organized being is required, a new and specific 



1 Chemistry of Common Life, vol. i. pp. 84, 85. 



2 Ibid., vol. i. pp. 298, 299. 



