46 SCIENCE PROGRESS 



attention has been given to the possibility of assimilative errors. 

 We have seen that there are now experimental grounds for 

 believing that the influence of the pancreas in carbohydrate 

 metabolism is exerted in connexion with some synthesis (of 

 which the formation of glycogen is possibly the first stage) 

 which precedes the final destruction of sugar in the body ; and 

 quite the last word upon metabolism, which Pavy would have 

 been pleased to hear, suggests that " carbohydrate in some 

 form or other is absolutely essential for the synthesis of protein 

 within the tissues." 1 Clearly we have not yet the knowledge 

 to appraise fully Pavy's views or any other views of a dogmatic 

 sort, concerning the metabolism of sugar or the significance of 

 diabetes. 



It may shock many who are unfamiliar with the recent 

 literature of physiology and pathology to learn that so few 

 statements of a definite sort can be made with regard to so 

 fundamental a matter as the fate of a basal foodstuff in the 

 body. It may chill the heart of those who, at the beginning 

 of their career, think of working at such problems, to view 

 what seems the small harvest of Pavy's fifty years of labour. 

 But Pavy had no sense of failure and none should be felt by 

 those who have shared with him the attack upon these prob- 

 lems. If in this slight review speculations rather than facts 

 have been prominent it is because, under the influence of Pavy, 

 we have been considering the most intimate side of metabolism, 

 This, from its very nature, is a region where experimentation 

 is extraordinarily difficult and only recently has any serious 

 attempt to explore it been made. Twenty-five years ago our 

 equipment for the venture was most inadequate and the time 

 has been mainly spent in preparation. Any one who will con- 

 sider how much better we are equipped now will admit that 

 the years have been well spent. 



i Owing to the labours of Emil Fischer and others, our 

 knowledge of the pure chemistry of the simpler carbohydrates 

 is both extensive and precise, so that when we seek evidence 

 as to the course of molecular changes in the cell the possi- 

 bilities and probabilities are for the most part clearly before 

 us. But more than this : the moment the significance of intra- 

 cellular enzymes became manifest biochemists made haste to 



1 Cathcart, The Physiology of Protein Metabolism (Longmans, 191 2), p. 120. 



