IT 



these experiments, since a more extended series by Swale Vincent has 

 failed to give a general confirmation of our results. 



The severe diabetes which, as shown by Minkowski, can be produced 

 in nearly all animals by total excision of the pancreas, has been held to 

 denote the normal production in this organ of some substance which is 

 indispensable for the utilisation of carbohydrates in the body. All efforts 

 to obtain a more exact idea of the nature of this pancreatic substance or 

 influence have so far proved in vain. Ordinary sugar, when placed in 

 contact with extracts of muscular tissues, undergoes oxidation ; and 

 Cohnheim states that this process is much accelerated if an extract of 

 pancreas be added to the extract of muscle. A repetition of Cohnheim's 

 experiments by other observers has shown that the effect is so small as to 

 be almost accidental ; and we must therefore regard the nature of the 

 pancreatic influence on carbohydrate metabolism and the causation of 

 pancreatic diabetes as problems still to be solved. 



So far (except in the case of the muscle respiratory centre reaction) 

 we have been dealing with isolated phenomena occurring in different parts 

 of the body, in which the reaction affects a whole series of tissues. The 

 chemical stimulus in these cases might be considered analogous to altera- 

 tions in the composition of the surrounding medium, and the reaction 

 lack that definite and localised character, which we have learnt to regard 

 as distinguishing the adaptations or reflex actions brought about by the 

 intermediation of the central nervous system. We have now to discuss 

 the mechanism of a whole series of chemical reactions where this feature 

 of a nervous reaction is not wanting, so that the reactions, until 

 quite recently, were regarded as undoubtedly nervous in character. I 

 refer to the chain of processes in the alimentary canal by which the 

 secretion of one juice succeeds that of another as the food progresses 

 along this tube. This series of reactions may well form the subject of a 

 separate lecture. 



