1898] 65 



OBITUARIES 



EUDOLF P. HEIDENHAIN 

 BoEN AT Marienwekder, Jan. 29, 1834. Died October 12, 1897 



Son of a medical practitioner, Heidenhain was from the year 1859 

 until his death, professor of physiology and histology at the University 

 of Breslau. He became celebrated principally through his work on 

 the physiology of the muscles and of the nervous system, and on the 

 functions of glands. 



The chief of his important researches on the muscles were his 

 Mechanische Leistung, Wdrmeentwickhing v.nd Stoffumsatz hei der 

 Musheltlidtigheit, Leipzig, 1864 ; his original experiments on the tone 

 of the muscles (1856), on muscular tetanus (1858), on pseudo-motor 

 nervous actions (1883), and a remarkable series of studies on the 

 innervation of vessels (1869-1878). To this series may also be added 

 the memoir, written in collaboration with Biibnoff — Ueber Erregungs- 

 iind Hemmungsncrven innerhalb der motorischen Hirncentren {Archiv. 

 f. die ges. Physiol., 1881), — which propounds and develops, although 

 hypothetically, one of the most important laws of nervous action, 

 namely, that in a normal state every excitation of a nerve-centre gives 

 rise to a process of opposite sensation, consequently tending to put an 

 end to the motion previously provoked. 



Amongst Heidenhain's works on the nervous system should be 

 quoted his researches on hypnotism (1880), which are some of the 

 best of physiological investigations of those complex phenomena. 



But it is in the vast field of glandular functions that Heidenhain 

 made his greatest discoveries. Most of his experimental results have 

 become classical — the application of the anti-secretory action of 

 atropine (discovered by Keuchel) to distinguish between the vaso- 

 motor nerves of the glands and the true secretory nerves ; the 

 determiuntion of the secretory nerve of the parotid (the glosso- 

 pharyngeal) ; the influence of the nervous system on the pancreatic 

 and bile secretions ; the variations of pressure in the excretory 

 passages of the glands ; the functional differentiation between the 

 glandular cells of the pyloric region and those at the bottom of the 

 stomach ; the formation of ferments in the cells of the pancreas ; the 

 function of various elements of the kidneys ; absorption in the small 

 intestine ; and finally a series of conceptions of deep interest on 

 ferment-producing substances and processes. 



Whatever the importance of the above, there are two works 

 which, by reason of their originality and suggestiveness, are superior 

 to all the rest of Heidenhain's results in this direction. It is well 

 known that he was the first to conceive the idea of studying the 

 histological modifications of glands after a prolonged excitation of the 



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