28 H. J. Sears 



on the 15th day of incubation the nitrogen so determined, amounts to 

 nearly 50% of the total nitrogen of the medium, we can scarcely agree 

 with Rettger's*^ observation that this bacillus is primarily a fermenting 

 organism. 



The initial reduction in amount of the free ammonia which is 

 originally present in the medium occurs in all of the cultures except 

 the sugar-free culture of B. subtilis. The probable reason for this 

 exception has already been suggested. In all cases this initial reduction 

 takes place until the ammonia value actually reaches zero, and there- 

 after, in a number of the cultures, this compound remains absent for 

 several days. This peculiar behavior was not shown by the pure pep- 

 tone cultures and therefore it must be ascribed to the presence of 

 gelatin. Obviously, the amino-acids resulting from the decomposition 

 of this protein are broken down to the form of ammonia to a much 

 smaller extent than those resulting from the splitting of Witte's pep- 

 tone. Probably in the presence of an abundance of nourishment the 

 decomposition is not carried so far. 



EVIDENCE OF THE EXISTENCnf OF CONSIDERABLE QUANTITIES OF 



NITROGEN IN COMPOUNDS INTERMEDIARY BETWEEN AMINO- 



ACID AND AMMONIA 



Investigators who have speculated on the manner in which the 

 amino-acids resulting from protein-decomposition by micro-organisms 

 are further broken down in the course of putrefaction have taught us 

 to suppose that the first reaction to take place is deaminization with 

 the splitting off of ammonia.*^ This would mean, of course, that all 

 the nitrogen of that group determined by the Van Slyke method, i. e., 

 the alpha amino nitrogen, is transformed into ammonia. That this is 

 not true in the case of the cultures investigated by us becomes evident 

 when the tables are studied more carefully. Every decrease in amino- 

 acid content which occurs in the interval between two analyses must 

 represent, of course, the minimal amount of this form of nitrogen 

 which has been altered during the period. If such alteration con- 

 sisted in large part or entirely in deaminization, then the decrease 

 should appear as a corresponding increase in ammonia nitrogen. The 

 instances in which this is true in the data given are so rare as to be 

 considered purely accidental. That this extra amount of amino-acid 

 nitrogen metabolized could be to any considerable degree accounted 

 for by ammonia lost through volatilization is made improbable from 

 the following experiment: Five cubic centimeters of a 2% peptone 



«» Jour. Biol. Chem., 1908, 4, p. 45. 



" Lafar: Handbuch der technischen Mykologie, 1904-1906, 3, p. 103. 



