CHEMICAL MECHANISMS OP SECRETION 191 



formed in the cells of the body itself upon the activity of the 

 secreting cells of pancreas and stomach open up to physiological 

 research a field of great importance, and one with practical bearing 

 for medicine and organo-therapy. Doubtless similar actions occur 

 elsewhere in the body which will in the future be brought to light. 

 Bayliss and Starling in their paper briefly draw attention to what 

 they term the chemical sympathies between uterus and mammary 

 gland, and to the modifications in the composition of the pancreatic 

 juice accompanying long-continued change in the diet, such, for 

 example, as the production of a laccase as the result of milk feed- 

 ing, and call attention to the advisability of a renewed investiga- 

 tion of these facts from the point of view of the production in 

 such cases of bodies allied to secretin. There is no doubt that 

 in many cases the stimulus to seasonal functional activity of 

 organs may be a chemical one. In this connection also might 

 be mentioned the occurrence of menstruation, and the seasonal 

 recurrence of rut in cattle, also the absence of these during preg- 

 nancy accompanying the changed chemical metabolism at such a 

 period, and the chemical changes going on in the corpus luteum 

 of the ovary. 



Thus the field of " internal secretion," which first began 

 to be explored in the case of the ductless glands, the thyroid 

 and suprarenal, goes on widening in scope, and we learn 

 afresh that an organ or cell, in addition to its most conspicuous 

 function, may possess other and no less important chemical 

 activities. 



Effects of Food upon the Production of the Digestive Secretions. A 

 number of most interesting and valuable observations have been 

 published from the Pawlow school, upon the effects of different 

 foods on the rate of secretion, and variations in this during the 

 period of digestion, and on the alterations in the quality of the 

 secretion resulting from the intake of different foods, and con- 

 tinuance upon different diets for more prolonged periods. The 

 series of experiments upon these points are very extensive, and 

 only a summary of results can be included in this article ; a 

 good account of the matter is contained in Pawlow's book on 

 u The Work of the Digestive Glands" (translated by W. H. 

 Thompson). 



1. Secretion under normal conditions only commences as a 

 result of food being taken into the alimentary canal. The miniature 



