l82 



THE ENERGY OF THE LIVING PROTOPLASM. 



The lateral chains of aromatic ketones are oxidised to carboxyl, 

 if the benzene ring does not contain a hydroxyl-group, otherwise 

 the entire compound will reappear in combination with sulphuric 

 or glucuronic acid in the urine, with the lateral chain preserved 

 {Ncncki). Some sulphur compounds will yield sulphuric acid, 

 while others will not. (I) 



It is, further, of great interest that the oxidation of benzene 

 to phenol and to small quantities of pyrocatechin and hydro- 

 quinone in the animal body {Ncncki and Giacosa) is diminished by 

 the introduction of certain poisons. (2) 



The difficulty in completely oxidising benzene derivatives of 

 a certain constitution is not only encountered in the animal but 

 also in the vegetal organism. Many plants accumulate tannins 

 and related compounds without ever utilising them again ; in 

 most cases they are excreted and may by their repulsive taste 

 prevent depredations by various animals : only under certain 

 conditions may tannin be utilised again. (3) Also certain alkaloids 

 in plants undergo no further metamorphosis (4) and have to be 

 looked upon as excreta. It is, further, very characteristic of 

 the oxidising faculties of plant-cells that certain compounds are 

 left unchanged, which, even by such a comparatively weak 

 oxidising agent as hydrogen peroxide, are attacked readily. Thus, 

 it was observed by Pfcffcr that cyanin (a quinoline derivative), 

 introduced into plant-cells is not altered, while it is easily bleached 

 by the peroxide. Also certain compounds in the roots of Vicia 

 and of Trianea Bogotcnsis are easily converted into brown oxida- 



(1) Compounds of the general formula NH2 — CO — S — R easily yield sulphuric 

 acid ; thiophen or sulphonal do not (Smith). 



(2) Nencki and Sicbcr (Pfliig. Arch. 319). found, e.g., that while in the body 

 of a healthy man 0.82 g. phenol was formed from 2 gram benzene, under normal 

 conditions, only 0.33 g. was formed if 2 gr. ethyl alcohol per kilo of body-weight were 

 administered at the same time. Also individual differences were noticed. Poisons 

 may also interfere with normal oxidising processes; thus, diamide in non-lethal doses 

 leads to the appearance of allantoin in the urine of dogs (Borisson, Z. physiol. Chem., 

 1», 499). 



(3) .Small kinds of Spirogyra will use up their tannin after a few weeks cultiva- 

 tion in a solution containing 0.5 oj 0 KH2 PO4 ; 0.2 o/ 0 KH C0 3 and traces of nitrate 

 and sulphate of calcium. 



(4) Cf. the investigations of Leo Errcra, Maistriau, and Clautriau, especially 

 those of the latter in the Bulletin Beige de Microscopie, 1894. 



