486 



selves derive the cyolic aiiiino-acids from these «ources, it being a 

 fact that protein, containing these amino-acids, is always present in 

 these organisms. 



In how far the amino-acids, formed in the |>aunch, are of nse 

 to the metabolism of ruminants, will have to be made out bj food- 

 experiments, which will also iiave to show whether the bacterial 

 protein, formed in the paunch, is resorbed. 



Let it be observed that we have never succeeded in demonstrating 

 tryptophane (or tyrosine) in the fresh turbid paunch-fluid (after the 

 removal of the solid particles) and also that we were not more 

 successful in this respect after cultivating foi' some days in the 

 incubator, either under aerobic or anaerobic conditions. 



Meanwhile we should not omit stating that reactions in a fluid 

 like the paunch-fluid, are far less sensitive than those in unstained 

 solutions. Only when 7 mgms of tryptophane per JOOcc. was added 

 in the form of protein (bloodplasma) a perfectly distinct tryptophane- 

 reaction was recognizable. 



Still, the phenomenon, just alluded to, does not point to an abund- 

 ant tryptophane formation in the paunch, which is the more 

 striking since the paunch fluid with Uschinsky's solution (10:25) 

 yields negative results at starting, but exhibits distinct reactions 

 after 2 X 24 hrs. 



The above experiments show: 1". that various bacteria present in 

 the paunch of cows can build up the amino-acids tryptophane and 

 tyrosine from ammonia nitrogen plus asparagine (or aspartic) nitrogen, 

 and also from urea as nitrogen-source. 



2'. that these bacteria can form quantities of tryptophane in the 

 culture-medium of Uschinsky, which may be of some significance 

 for the metabolism in cows; however it is not quite certain whetlier 

 this synthesis is equally intense in the paunch. 



{From the Chem. Labor, of the Utrecht Veterinary Univ.) 



