1911.] 



Anniversary Address by Sir A. Geihie. 



44 5 



the small intestine, the whole question was in the utmost confusion. For 

 the first time these observers showed conclusively that the movements of 

 the intestine are under the control of a local nervous system ; and, even 

 to the present time, the intestines are the only organs in higher animals 

 which have been shown to be the seat of a local nervous system capable of 

 carrying out co-ordinated reflexes. 



A fourth group of papers deals with the mechanism of the pancreatic 

 secretion. These researches, which by themselves would be sufficient to 

 justify the award of the Eoyal Medal, were also carried out in partner- 

 ship with his colleague, Prof. Starling. For many years physiologists have 

 assumed the production of internal secretions by different organs which 

 might influence other parts of the body. In these researches on the 

 pancreas the first definite proof was brought forward of the production of 

 a chemical substance in one organ, the duodenum, and its passage by the 

 blood to another organ, the pancreas, as a result of events occurring in 

 the duodenum. The secretion of pancreatic juice on the entry of the acid 

 chyme into the duodenum had been previously regarded as a nervous reflex. 

 Bayliss and Starling showed that it was a chemical reflex, i.e., effected by the 

 production of a specific chemical messenger which travelled by the blood, 

 and not by the stimulation of nerve endings and the passage of impulses 

 through nerves and the central nervous system. They showed, moreover, that 

 this secretin was but a type of a whole group of substances which they 

 designated hormones. The discovery of these hormones, and the precise 

 definition of their nature and of the conditions of their activity, mark an 

 important epoch in the development of our knowledge of the organs of the 

 animal body. 



The discovery of secretin afforded for the first time a convenient and easy 

 method of obtaining pancreatic juice in large quantities. The investigation 

 of the properties of pancreatic juice and of the activation of its chief 

 proteolytic ferment by another ferment, enterokinase, secreted by the 

 intestinal mucous membrane, has led Bayliss to a further series of researches 

 on the mode of action of enzymes and on the closely related questions with 

 regard to the nature of colloidal solutions. The value of this work has been 

 universally recognised. The book on the nature of enzyme action in which 

 Bayliss' researches are summarised has already appeared in German, while 

 his most recent work on the osmotic pressure of colloids, as studied in 

 solutions of colloidal dye-stuffs, is a model of the manner in which such 

 investigations should be carried out. 



