1O4 Lectures on Bacteria. [ ix. 



A point of great importance to notice here is the liquefaction 

 of the gelatine which occurs in cultures of some Bacteria, for 

 example Bacillus subtilis and B. Megaterium, but not in all. 



And here the many-sided Bacillus Amylobacter must again 

 be mentioned. According to the researches of Fitz and Hueppe, 

 this Bacillus decomposes the casein of milk in the following 

 manner : the casein first coagulates as when rennet is employed, 

 the effect being produced by the enzyme disengaged by the 

 Bacillus ; it then becomes liquid and is converted into peptone, 

 and then into further and simpler products of decomposition, 

 among which leucin, tyrosin, and ultimately ammonia, have 

 been ascertained. The fluid meanwhile acquires a more or 

 less pronounced bitter taste. Similar if not identical effects 

 on the casein of milk were observed by Duclaux to pro- 

 ceed from the Bacilli which he names Tyrothrix (see page 52), 

 the greater part of which must also morphologically approach 

 near to B. Amylobacter. Tyrothrix tenuis, for example, first 

 produced the coagulation of rennet, then liquefaction, and after 

 that formation of leucin, tyrosin, ammonium valerianate, and 

 ammonium carbonate. There can be no doubt that these 

 changes, and others connected with them, are the essential part 

 of the phenomena which constitute the process of ripening of 

 the cheese prepared from .the coagulated milk, the above-named 

 Bacteria, with some others, being contained in the cheese, and 

 being procurable from k for the purpose of examination. 



Bienstock (50) has recently submitted the Bacteria of human 

 faeces to careful examination, and found that in those of adults, 

 besides other forms which are unimportant in reference to the 

 processes in question, there is always a particular Bacillus 

 present, which he regards as the specific cause of putrefaction 

 not only of the bodies contained in the faeces, but of those 

 which contain albumin and fibrin. This Bacillus in a pure 

 culture is able of itself to separate albumin or fibrin into the 

 successive products of decomposition which have been ascer- 

 tained in other cases of putrefaction up to the latest and final 



