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CHAPTER III. 



On the Origin of Ferments properly so called. 



The new process of brewing-, which it is the principal object of 

 this work to explain, and which will follow as an immediate and 

 inevitable deduction from the novel facts herein demonstrated, 

 cannot be fully understood without a knowledge of all the 

 principles upon which it is founded. One of the most essential 

 of these has reference to the purity of our fermentation. We 

 should gain but little from the use of a yeast uncontaminated 

 by any foreign germs if natural organic substances had the 

 power of organizing themselves by means of spontaneous gene- 

 ration, or by some transformation which took place amongst 

 them, or even by a conversion of certain microscopic beings 

 into certain others. Theories of this kind are still warmly ad- 

 vocated, but, to our thinking, rather from sentimental considera- 

 tions or prejudice than from any basis of serious experimental 

 proofs. 



Be this as it may, we must free our minds from all suppo- 

 sitions which might qualify the exactness of the principles upon 

 which our new process is founded, or cause any doubt in the 

 minds of our readers as to the possibility of its application and 

 the benefits to be derived from its adoption. 



§ I. — On the Conditions which cause Variations in the 

 Nature of the Organized Products existing in 

 Infusions. 



We have proved by experiment, in the preceding chapter, 



