iQis] R. H. A. Plimmer 4^9 



ture, the growth ceased immediately, being resumed when arginine 

 and histidine were again added. The removal of tryptophane from 

 the amino-acid mixture also produced similar results ; and Osborne 

 and Mendel in America had shown cystine to be similarly essential. 

 It did not follow that this was the case with every amino-acid, and 

 the question as to which of the amino-acids were essential in that way 

 offered a large field for investigation. Recent work at Cambridge 

 indicated that certain acids could be removed from the amino-acid 

 mixture without affecting the rate of growth. With regard to the 

 minimum quantity of any amino-acid required for nutrition, experi- 

 ment had shown that, in the case of rats, at any rate, the critical 

 minimum for arginine lay somewhere between 2.5 and i percent. 

 It appeared that the functions of the individual amino-acids were 

 not confined merely to flesh formation. The effect of feeding ani- 

 mals on zein, which was deficient in both tryptophane and lysine, 

 was not only to restrict growth but also to shorten the survival, and 

 the same was observed with zein plus lysine; but with zein pliis 

 tryptophane the animal was able to maintain its weight for a long 

 period, although it did not grow. It was clear from this that the 

 tryptophane exercised some other function than the mere supply of 

 material for growth. Further work on this subject is proceeding at 

 Cambridge. 



Dr. E. P. Cathcart, referring to creatine and Creatinine, said that 

 the observations at present available were so scanty that it could not 

 be stated with certainty that creatine and Creatinine had a special 

 niche in the organism. Creatinine, of course, was a constant ex- 

 cretory product, but creatine was not, except in the case of infants, 

 though it might be made to appear if an animal were starved or 

 treated with certain drugs. Folin had stated that creatine was a 

 fairly valuable food-stuff, but he (Dr. Cathcart) did not think, on 

 the evidence available, that it was. He did not think that any end 

 would be gained by the separate estimation of creatine and Creatinine 

 in meat extract, since a large part of the original creatine would prob- 

 ably be converted into Creatinine during the process of manufacture. 



Mr. A. R. Tankard thought that it was important in some cases 

 to separately estimate the meat fibre and coagulable albuminoids, 

 with a view to the detection of extraneous matters which were some- 



