i;o SCIENCE PROGRESS 



biogens in the form of an N0 2 grouping attached to a benzene 

 ring, and that one atom of oxygen from the N0 2 oxidises the 

 — CHO or — CHOH groups of the carbohydrate molecule to 

 C0 2 and water. 



The hypothesis that the respiratory processes of tissues are 

 carried out by non-nitrogenous side chains is borne out by some 

 curious and unexpected results obtained by the writer. It was 

 found that when recently excised mammalian kidneys were per- 

 fused with saline solution, the protoplasm of the tissues was in 

 a state of such extreme instability that it was liable to undergo 

 sudden disintegration, whereby a good deal of proteid, proteid 

 decomposition products and intracellular ferments (such as 

 erepsin) passed out into solution. In various experiments 

 carried out under normal conditions, from 9 to 17 per cent, 

 of the total proteids present in the kidney tissues were washed 

 out during the course of an eleven-hour perfusion, and yet the 

 respiratory powers of these kidneys were just as great as those 

 of other kidneys in which there had been little or no tissue 

 disintegration. 



The carbohydrate-like nature of the side chains receives 

 support from the above-mentioned facts concerning lactic acid 

 formation in the tissues. We know that sugars are converted 

 into lactic acid not only by the action of various bacteria, but 

 also by intracellular enzymes such as the lactacidase enzyme of 

 the expressed juice of yeast (Buchner and Meisenheimer). Such 

 lactic acid formation may be a normal stage in the oxidation of 

 the carbohydrate-like chains to C0 2 , or it may be an exceptional 

 one, occurring but seldom unless the conditions of oxidation in 

 the tissues are deficient. If the — CHOH groupings of the 

 carbohydrate side chains are oxidised one at a time, they would 

 presumably pass through an aldehyde stage first. That an 

 aldehyde stage does occur at some point or other in the course 

 of tissue respiration, seems to be borne out by some observations 

 of the writer. Thus it was found that if an excised mammalian 

 kidney were perfused with saline containing *i to '2 per cent, of 

 hydrocyanic acid, its gaseous metabolism, when estimated shortly 

 after in the usual way by perfusion with normal oxygenated 

 saline, was at a minimum at first, but that it steadily increased 

 for the next eleven hours. During the perfusion, small quantities 

 of HCN broke away from the tissues, and hence it was surmised 

 that this HCN was bound up to —CHO groups so as to form 



