242 SCIENCE PROGRESS 



In addition to the methylated bases derived from amino-acids, 

 methylated amino-acids may also be present in plants. Thus 

 a monomethyltyrosine (surinamine) is said to occur in several 

 plants. If the nitrogen be completely methylated, an internal 

 salt may be formed by interaction of the amino and carboxyl 

 groups ; the so-called betaines are thus produced. The best 

 known of these substances is trimethylglycine or betaine, so 

 called because it was found originally in Beta vulgaris; it is 

 obtainable in large quantities from the sugar beet and even 

 forms a commercial source of trimethylamine. Owing to the 

 accumulation of methyl groups, betaine is much more basic 

 than glycine and forms a stable hydrochloride. 



Stachydrine is the betaine of a-pyrrolidinecarboxylic acid 

 or proline, a common fission product of proteins : 



CH„— CH 2 CH— CH 2 



II II 



CH 2 CH— CO CH, CH.COOH 



\/ i \/ 



N NH 



/\ 



CH, CH 3 



Stachydrine Proline 



Stachydrine has so far only been found in the tubers of Stachys 

 tubifera and in the leaves of Citrus aurantium but is perhaps 

 more widely distributed. 



A more complicated betaine is that derived from tryptophane, 



r^^ n c . CH 2 . CH— CO 



S^-k^ CH N O 



NH III 



(CH 3 >, 



This substance occurs to the extent of 3 per cent, in the seeds 

 of an Indian tree, Hypaphorus, in which it has been found by 

 Greshoff, who described it as an alkaloid, hypaphorine. It has 

 been prepared recently from tryptophane by Van Romburgh 

 (Proc. Acad. Set. Amsterdam, March 25, 191 1). 



Kutscher has isolated from a commercial mushroom extract 

 a base having the composition of the betaine of histidine. 

 Although the betaines, like the decarboxylated amino-acids, 

 are basic, they are physiologically inert, on account of the 

 presence of a carboxyl group. 



