THE BEGINNINGS OF LIFE. 401 



solution of which many distinguished chemists have 

 been induced to devote much time and labour. The 

 ground is in fact common to biologists and chemists, 

 and the question is so obscure and difficult that it 

 stands much in need of the double illumination. 

 Important, however, as are the considerations which the 

 chemist brings towards its solution, and valuable as are 

 the methods which he employs, the problem is, never- 

 theless, so all-important in its biological aspects that 

 it cannot with advantage be wholly relegated to him. 



M. Pasteur frankly tells us that, having formed cer- 

 tain views concerning the cause of fermentations in 

 general, he found himself compelled to come to an 

 opinion c sur les questions des generations spontanees.' 

 And here some words of explanation seem needed, in 

 order to show more fully how the two problems are 

 so inseparably related, and as well that the reader 

 may comprehend the nature of the doctrines which are 

 held by many other chemists, in opposition to those of 

 M. Pasteur. 



We are now becoming better acquainted with a set of 

 remarkable changes that certain compound substances 

 are apt to undergo, and which have usually been known 

 by the generic name of ( Fermentations V The prevail- 

 ing opinion had been that for the occurrence of such a 



Those which are accompanied by the evolution of foetid gases (see 

 p. 266. note 1} have usually been spoken of as putrefactions. The old 

 view of Mitscherlich ('Ann. Chem. Pharm.' xlviii. p. 126) was that 

 'fermentation is caused by a plant organism, and putrefaction by an 

 animal organism.' No such distinction can, however, be drawn. 

 VOL. I. D d 



