40 THE WORK OF THE DIGESTIVE GLANDS. 



calls into play the chemical activity of the gland cells, and thereby 

 brings on the secretion of saliva. This nerve receives the name of a 

 " secretory " or " katabolic " nerve. Heidenhain,* the late physiologist 

 of Breslau, carrying the matter farther, produced undoubted proof that 

 the secretion of saliva in the glands, resolves itself into two processes ; 

 to wit, the production of the watery and inorganic constituents of the 

 secretion, and the preparation of a specific organic body, the ferment. 

 Corresponding to these two subdivisions of the process, Heidenhain, 

 and with him the majority of physiologists, recognise two kinds of 

 special nerve-fibres which govern the activity of the salivary glands. 

 The one influences the secretion of water and of the inorganic salts 

 which it holds in solution, the other leads to an accumulation of the 

 organic body, the specific agency of the secretion. For the former, 

 Heidenhain retained the old name of " secretory " nerve, the latter he 

 termed " trophic." It has also been termed an " anabolic " nerve. 



The question as to whether the gastric glands have likewise a special 

 secretory innervatiori is now a very old one and has had an interest- 

 ing career. In this matter physiology stood for a long time in sharp 

 conflict with practical medicine. Physicians bringing forward their 

 observations in proof, had long answered the question in the affirmative, 

 and looked upon the existence of secretory nerves to the stomach a a 

 undoubted. They had even come to recognise different morbid con- 

 ditions of the innervation apparatus. Physiologists, on the other hand, 

 had fruitlessly endeavoured for decades to arrive at definite results 

 upon this question. This is a striking, but by no means isolated, 

 instance where the physician gives a more correct verdict concerning 

 physiological processes than the physiologist himself ; nor is it indeed 

 sti^ange. The world of pathological phenomena is nothing but an 

 endless series of the most different and unusual combinations of physio- 

 logical occurrences which never make their appearance in the normal 

 course of life. It is a series of physiological experiments which nature 

 and life institute, often with such an interlinking of events as could 

 never enter into the mind of the present-day physiologist, and which 

 could scarcely be called into existence by means of the technical resources 

 at his command. Clinical observation will consequently always remain 

 a rich mine of physiological facts. It is therefore only perfectly natural 

 that the physiologist should endeavour to maintain a close connection 

 between his science and that of medicine. 



Notwithstanding the wide range and perplexing nature of the 

 literature of the innervation of the gastric glands, we are fortunately 



* R. Heidenhain, Studien des irttyxtol. Inatltidx zu lirrxluii. iv. 18(!8 and 

 I'll iiger's Arckir. Bd. xvii. 1878. 



