194 BIBLIOGRAPHY 



again to bread and milk, similar but inverse changes are observed. 

 The moral from this for practical medicine, which experience had 

 already indicated, is that a sudden change from one regime to 

 another may have a disastrous effect upon the digestive process, 

 by subjecting the glands to a strain to which they have not been 

 adapted. Hence changes in dietary should be brought about 

 slowly and progressively wherever possible, and not by a sudden 

 and sweeping change. 



The physiological causes and mechanisms of this interesting 

 adaptation in quantity and quality of the digestive fluids to the 

 nature of the food are as yet obscure to us. 



Pawlow, their chief discoverer, ascribed them to a differentiated 

 peripheral nerve supply in the mucous membrane of the alimentary 

 canal, whereby the absorption of different digested food- stuffs 

 stimulated different nerve endings, fibres, and cells, and caused 

 a discharge of correspondingly different efferent stimuli to the 

 gland cells, as also to the variation in amount and kind of 

 psychical stimulation by the variation to sight and smell of differ- 

 ent sorts of food. 



This explanation was given, however, before the days of Bayliss 

 and Starling's discovery of the chemical excitants to secretion, 

 and the question now remains an open one whether the nervous 

 system has anything, and if so how much, to do with the adapta- 

 tion of secretion to food, and with the characteristic variations 

 above described of rate and progress of secretion with the nature 

 of the food. 



In the light of our new knowledge the whole subject of secretion 

 stands ripe for investigation, and is rich in promise of new addi- 

 tions to our knowledge, of the highest value to physiology and to 

 medicine. 



BIBLIOGRAPHY 



Overton, Studien iiber die Narkose, Jena, G. Fischer (1901) ; Jahresbuch 

 f. wiss. Botanik, vol. xxxiv. (1900), p. 669 ; Vierteljahrschrift d. Naturf . 

 Gesellsch. in Zurich, vol. xliv. (1899), p. 128. 



Hober, Physikalische Chemie der Zelle imd Gewebe, Hirzel, Leipzig 

 (1902). 



Hamburger, Osmotisclier Druck und lonenlehre, Wiesbaden, J. F. Berg- 

 inarin, Bde. i., ii., iii. (1901-1904). 





