28 SCIENCE PROGRESS 



they are formulated. Proteins are not glucosides. In the first 

 place, the group present in their molecule is not strictly a 

 carbohydrate group. What is really obtained on hydrolysis is 

 a nitrogenous derivative of dextrose (glucosamine). This sub- 

 stance contains an amino-group and so bears a relation to the 

 other constituents of protein — the amino-acids. Its constitu- 

 tion is such that it yields an osazone identical with that given 

 by dextrose, so that the evidence relied upon by Pavy to prove 

 the production of the latter was misleading. The substance 

 is not yielded by all proteins and is probably absent from the 

 molecules of typical blood proteins, the amount obtainable from 

 the serum-albumen being so small as to suggest that it arises 

 from some impurity. What is of special weight against Pavy's 

 views as regards its significance is the fact that glucosamine 

 does not behave as a carbohydrate in the body ; it yields, for 

 instance, no glycogen to the liver. 



With regard to transport, we find that, at the end, Pavy 

 was willing to simplify his views. He had been struck by a 

 paper by Bayliss dealing with " adsorption " as a preliminary 

 step to chemical action and seems to have decided that the 

 existence of a loose compound of circulating sugar with the 

 blood proteins will account for the failure of the latter to be 

 excreted. 1 In the paper already mentioned as published after 

 his death he wrote : " After adsorption taking place, the sugar, 

 whilst recoverable (from the blood) by analysis, would be virtu- 

 ally holding a colloidal position and in this state would escape 

 being eliminated by the kidney." 



I think it must be admitted that Pavy's final position with 

 regard to the function of the liver in the metabolism of carbo- 

 hydrates does not differ vitally from that of Claude Bernard nor 

 that of the present-day majority. He held, it is true, that 

 the liver does not deal with all the sugar absorbed from the 

 intestines but only with a part of it. He came to admit, however, 

 that the hepatic glycogen arises directly from the carbohydrate 

 of food, that it represents a store held in trust for the tissues 

 and that it is mobilised for transport by an enzyme which 

 converts it into sugar. The added view that during transport 

 it is not strictly free but forms a loose compound with the 

 blood proteins does not carry us far from the teaching of 



1 The view had been previously advanced by Otto Loewi, Archiv fur exp. 

 Path, und Pharm. xlviii. 410 (1902). 



