PRACTICAL RESULTS OF BACTERIOLOGY. 737 



urine; those which produce marsh gas by the fermentation of 

 cellulose ; those which effect the decomposition of albumin, with 

 an evolution of hydrosulphuric acid ; those which give rise to the 

 putrefactive decomposition of organic material, the number of 

 which is very large ; the bacteria in the soil which reduce nitrates 

 with liberation of ammonia and free nitrogen, and those which 

 oxidize ammonia. The study of these bacterial ferments is still 

 being vigorously prosecuted, and practical results of importance 

 in agriculture and the arts have already been attained. In the 

 future we may look for numerous additions to these practical 

 applications of our knowledge. The use of pure cultures for pro- 

 ducing useful fermentations must give the best result with the 

 least liability to loss of material from the presence of undesirable 

 species. It is known that the flavor of butter and of different 

 kinds of cheese is due to various bacterial ferments, and there is 

 good reason to suppose that a better product and greater uni- 

 formity would be attained by the use of pure cultures of the 

 species upon which special flavors depend. I understand that in 

 this country quite a number of dairies are now using pure cul- 

 tures of a certain bacillus (Bacillus 41 of Conn) for giving flavor 

 to their product. It is probable that similar methods will soon 

 be introduced in the cheese-making industry. A recent Eng- 

 lish publication, which I have not yet seen, is entitled Bread, 

 Bakehouses, and Bacteria. It will, no doubt, be found to con- 

 tain information of practical value to those engaged in bread- 

 making. 



Pasteur's studies relating to the micro-organisms causing ab- 

 normal and injurious fermentations in wine, the results of which 

 he published in 1866 (Etudes sur le Vin, ses Maladies, etc.), have 

 resulted in an enormous saving to the wine-making industry in 

 France and other countries where wine is produced upon a large 

 scale; and his investigations relating to the cause and preven- 

 tion of the infectious diseases of the silkworm, which threatened 

 to destroy the silk industry in France, have resulted in even 

 greater benefits to the material interests of his country and of the 

 world (published in 1870). 



Agricultural chemists predict that in the near future cultures 

 of the nitrifying bacteria of the soil will be made on a large scale 

 for the use of farmers, who will add them to manures for the 

 purpose of fixing the ammonia,, or perhaps will distribute them 

 directly upon the soil. Should this prove to be a successful and 

 economic procedure, the extent of the interests involved will 

 make it a "practical result" of the first importance. Another 

 application of our recently acquired knowledge which has already 

 proved useful to farmers in certain parts of Europe relates to the 

 destruction of field mice by distributing in the grain fields bread 



VOL. XLVIII. 53 



