24 SELMAN A. WAKSMAN 



quantities of ammonia are much smaller; this again brings out the 

 fact that, while the proteolytic bacteria and molds allow a rapid 

 accumulation, the actinomycetes will produce only small quan- 

 tities of ammonia in a short period of time, the ammonia tend- 

 ing to increase with the prolongation of the period of incubation. 



The presence of starch in gelatin seems to exert in many 

 instances a protective action upon the gelatin, and, though a 

 better growth might have been obtained in the presence of 

 starch, there was less of the gelatin split. This does not hold 

 absolutely true for all species; in a few instances there was a 

 greater splitting of the gelatin in the presence of starch. On 

 the average, however, there was a greater accumulation of 

 amino-nitrogen in the gelatin in the absence of starch than in 

 its presence. The gelatin containing originally 6.35 to 6.41 

 mgm. amino nitrogen in 10 cc, was found, at the end of the 

 period of incubation, to contain, on an average, 27.93 mgm. of 

 NH 2 -N, in the presence of 1 per cent starch, and only 21.72 

 mgm., in the absence of starch. This is in accord with the 

 investigations of the writer and others which indicate that 

 available carbohydrates exert a protective action upon the 

 proteins. 



To get a further insight as to the effect of available carbo- 

 hydrates upon the splitting of proteins by actinomycetes and 

 compare these organisms in this respect with bacteria and molds, 

 the following experiment was made. One lot of ordinary bouil- 

 lon was made up and divided into 2 portions; 1 per cent glucose 

 was added to one half and the other half left unchanged. These 

 media were distributed in flasks, sterilized and inoculated, as 

 usual in duplicates, with B. coli, B. proteus, Aspergillus niger 

 and 5 species of Actinomyces. The flasks were incubated at 

 37° and, at the end of seven days, the amino and ammonia- 

 nitrogen were determined. The data are given in table 7. 



The addition of 1 per cent glucose causes, in the case of all 

 microorganisms, a lesser splitting of the proteins and peptones 

 accompanied by a smaller ammonia accumulation. But, while 

 the active proteolytic bacterium (B. proteus) and mold (A. niger) 

 were greatly repressed in their action upon the proteins and in 



