752 UVRES DE PASTEUR 



and finding that such solutions speedily became turbid l'rom the growth of 

 living organisais, it was proved that the air which had passed through the 

 gun-cotton had lost its property of causing the development of lil'e in solutions 

 because the germs which the air contained had been stopped by the gun- 

 cotton. 



The resuit of the second part of the research may be thus summed up: 



1. No organisms are developed in solutions il care be taken to prevent the 

 possibility of the prsence of germs. 



2. This ngative resull does not dpend upon the exclusion of oxygen. 



3. The matter separated from ordinary air is comptent to develop orga- 

 nisms in solutions which previosly had remained unchanged. 



Not less important were the results of Pasteurs experiments respecting 

 the chemical functions of the ferment. 



It had bien held that the entire ferment was in a state of putrefactive 

 dcomposition, and induced a similar dcomposition in the sugar with which 

 it was in contact. 



In corroboration of this view, it was stated that ammonia (a product of 

 the dcomposition of albuminous substances such as those prsent in the 

 Ferment) is always found in liquids which are undergoing fermentation. 



Pasteur proved that the ammonia in fermenting liquids diminishes in 

 quantity in proportion as the process advances, and that the yeast-cells 

 increase and grow while forming complex albuminous substances at the 

 expense of the ammonia and other aliments which are supplied to it. Ile 

 found that. in addition to ammonia and sugar. the cells require minerai 

 substances, such as phosphates and other constituents, such as are prsent 

 in the oreranism of'every hcalthv and ffrowing veast-ccll. 



In short, he proved that those conditions w hich are mosl favorable to the 

 hcalthv growth and development of the yeast-cells are most conducive to the 

 progress of fermentation, and that fermentation is impeded or arrested by 

 those influences which check the growth or destroy the vitality of the cell. 



The above results are but samples of the fruits of Pasteur s long sries ol 

 researches in this subject. Many and mauy an able investigator had worked 

 in the same field ; and such were the difficulties thej encountered, tha 

 Dumas himself recommended Pasteur not to waste liis time in vvorking at so 

 hopeless a subject. 



To the bioloerist, two of Pasteur' s researches are of verv grai interestand 



importance. Ile lias shown that fungi lind ail the materials uecded for their 



nutrition and erowth in water contamina: an ammonia sait and certain 



- 

 minerai constituents, and devoid of any uiti'Ogenized organic mat 1er : and ne 



had proved that ail the phenamena presented by the destructive silk-worm 



pidmie, the pbrine even the singular Tact tha il is hereditarily transmit- 



ted throush the female and not through the maie;, are to be explained by 



the prsence of a parasita- organism m the diseascd caterpillars. 



