THE METABOLISM OF PLANTS. 221 



plants. With regard to the possible destructive formation of 

 the proteid, there can be little doubt that it may be derived 

 from living protoplasm. If we regard the molecule of living 

 protoplasm as more complex than that of unorganised pro- 

 teid, we may infer that proteid may be one of the products 

 of the decomposition of the protoplasm-molecule. The 

 amides, as we have seen (p. 191), are produced from proteid 

 either by the action of an unorganised ferment, or by the 

 fermentative action of the living protoplasm ; in the latter 

 case the process would be probably one of oxidative decom- 

 position, for it has been found possible to obtain the amides 

 from proteid in this way by artificial means. 



The following is an enumeration of the substances of this 

 kind which have been found in plants. 



1. Amides : 



Asparagin, C 4 H 8 N 2 O 3 probably the amide of succinamic acid, C 2 H 8 , 



NH 2 , CONH 2 , COOH. 

 Glutamin, C 5 H 10 N 2 O 3 , probably the amide of glutaminic acid, 



C 3 H 5 , NH 2 , CONH 2 , COOH.' 



2. Amidated fatty acids : 



Leucin, G^^NOa, amidocaproic acid, C S H 10 NH 2 COOH. 

 Betain, C 5 H U NO 2 , possibly trimethyl-glycocoll, C (CH 8 ) 2 , NHCH 8 , 

 COOH, or oxyneurin C(CH 3 ) 3 NH 2 , O, CO. 



3. Amidated fatty acids containing an aromatic radicle : 



Tyrosin, C 9 H n NO 3 , probably a parahydroxyphenylamidopropionic 3l 



acid, C 2 H 3 , NH 2 , C 6 H 4 , HO, COOH. 

 A body, C 9 H U NO 2 allied to Schiitzenberger's tyroleucin, has been 



found by Schulze in Lupin-seedlings: it is probably phenylamido- 



propionic acid, C 2 H a , NH 2 , C 6 H 5 , COOH. 



4. Bodies belonging to the xanthin-group : 



Xanthin, C 5 H 4 N 4 O 2 , hypoxanthin, C 5 H 4 N 4 O, and guanin, C 5 H 6 N 6 O, 

 have been found by Schiitzenberger in Yeast, by Salomon in 

 Lupin-seedlings, by Reinke and Rodewald in ^Ethalium, and 

 Schulze and Eugster believe that they have found them in 

 potatoes. Kossel, who has found them in various plants, is of 

 opinion that they are derived from nuclein. Allantoin, C 4 H 6 N 4 O3, 

 has been found by Schulze in the young leaves of the Plane. 



The view that the amides are products of processes of 

 oxidative decomposition is supported by the fact that the 



