485 



The histidine reactions thus far obtained, were still somewhat 

 doubtful. 



Several naicroscopic preparations were made of the cultures. Some- 

 times different species were present, i.e. diplococci, rod-shaped bac- 

 teria; sometimes staphylococci and streptococci; in one case the 

 predominance of one species was such as to render it difficult to 

 find another. These almost pure cultures were not always made np 

 of the same bacteria; sometimes thej^ were small ovoid, at other 

 times rod-shaped bacteria. 



It being known that even various stocks of one and the same 

 species may differ largely as to the chemical changes they engender, 

 we did not ascertain whether the developing species were in any 

 way concerned in the result of the reaction. 



According to an approximate quantitative determination in a 

 culture, three days old, the sediment of 100 cc. contained about 

 3 mgms of tryptophane, i.e. per Liter 30 mgms, or 3 grms per 

 100 L. (putting the paunch contents at 100 L.). 



A man of 70 k.g. weight requires per day about 27, — 3 grms 

 of tryptophane. Assuming the same ratio for a cow, this animal 

 would require per day about 177^ — 20 grms. The quantity necessary 

 for the producton of milk has not been taken into account here. 



Putting the tryptophane content of milk per L. at about 750 mgms, 

 and putting the daily flow of milk at, say, 12 Liters, the animal 

 would have to take in another quantum of 9 grms of tryptophane. 



As far as we are aware tryptophane synthesis by bacteria (B. 

 coli and B. Frieülander) from ammoniac and aliphatic nitiogen- 

 compounds, has been demonstrated only once, viz. by Logie^- 



From the publication of Braun and Cahn — Bronner'), which came 

 to our notice when our experiments had nearly come to an end, 

 it may be inferred that their experiments also pointed to trypto- 

 phane synthesis, for they could grow coli, paratyphoid-, and Fried- 

 LANDER-bacteria when ammonia nitrogen was the only source of 

 nitrogen present. Where they report, that under perfectly anaerobic 

 conditions ammoniac-assimilation is impossible, even after the suppl}'^ 

 of more energy, the question rises (granting their theory to hold 

 generally) whether in the rumination process an aerobic condition 

 exists which allows any synthesis worth mentioning. 



It may rationally be supposed that, wherever micro-organisms 

 manage to live on inorganic or aliphatic nitrogen-sources, they them- 



1) J. of Pathol, and Bact. Bd. 23, 224 (1919/1920). 



2) Biochem. Zeitschrift Bd. 131, 272 (1922). 



