CAGNIARD-LATOUR, SCHWANN, HELMHOLTZ 63 



The experiments, when repeated, were not always 

 successful, especially when, instead of working with 

 sugared musts, organic infusions were used. But how 

 separate, in their causes and origins, phenomena so 

 evidently analogous as fermentation and putrefaction? 

 Opinion remained, therefore, a little hesitating, and th e 

 best proof that the old ideas were not disturbed is the 

 work of Helmholtz published in 1843, the first work of 

 the illustrious physicist. 



Helmholtz repeated with success the experiment 

 of Schwann, and asked himself what is this something 

 in the air which heat kills, or renders inactive. 

 It may be, he said, only a putrid exhalation coming 

 from a mass undergoing fermentation, and capable, 

 by virtue of an unknown power, of provoking a new 

 fermentation: or else it is a living germ. In the latter 

 case, the germ is insoluble in water. The putrid ex- 

 halation is, on the contrary, soluble and therefore dif- 

 fusible. Let us take, therefore, two vessels separated 

 by a membrane; in one let us place a liquid under- 

 going fermentation, or putrefying, in the other a liquid 

 of the same nature but not fermenting, and let us see 

 what will happen. If the fermentation does not 

 cross the membrane, then it is produced by living 

 creatures; if it does pass the membrane, it must be 

 attributed to something else. 



Now the experiment is always successful with liquids 

 undergoing alcoholic fermentation, and rarely or never 

 with macerated meat. That is, the presence of the 

 membrane prevents the alcoholic fermentation from 

 passing, but does not arrest the cause of putrefaction, 

 whatever it may be. From this Helmholtz concludes 

 that there are two kinds of transformation of organic 

 matter, one which takes place with the concourse of 

 microscopic organisms, and the other without them. 



