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SCIENCE 



[N. S. Vol. XL. No. 1030 



seventy-five years old, death surprised him in 

 the midst of scientific activity. He attended tlie 

 last meeting of the German Congress of Physi- 

 ologists at Berlin where, on the fifth of June, 

 he demonstrated experiments which should 

 support the neurogenic theory of the origin of 

 the heart beat. On his way home he stopped 

 at Nauheim, to inspect an apparatus which 

 he installed there for the study and use in 

 cardiac diseases. His death came there, sud- 

 denly, like a flash — perhaps by means of the 

 cardiac center which he discovered thirty years 

 before. 



Kronecker was one of the last of a classical 

 period in German physiology. He was pupil, 

 assistant and intimate friend of the master 

 minds of that period: Helmholtz, du Bois- 

 Eeymond and Carl Ludwig. At the same 

 time, he was master and friend of many lead- 

 ing physiologists of a later generation and of 

 many countries; he was an international leader 

 in his science. 



He was born in Liegnitz, Prussia, from a 

 well-to-do family with scientific proclivities. 

 The celebrated mathematician Leopold Kro- 

 necker was his older brother. After finishing 

 his general education at the Gymnasium in 

 Liegnitz he studied medicine in Berlin, Heidel- 

 berg and Pisa (Italy). In Heidelberg he 

 came under the special influence of Helmholtz, 

 who introduced Kronecker into the science of 

 physiology. The problem of muscular fatigue 

 which Kronecker studied first under Helmholtz 

 and which he treated in his thesis became the 

 source of many important investigations which 

 he carried out at various times during his 

 scientific career. In 1865 he became assistant 

 to Traube. This celebrated clinician was the 

 first mian to employ experimental physiology 

 for the study of medical problems. It was 

 probably due to the early influence of Traube 

 that Kronecker acquired the inclination to 

 make results, obtained in physiological studies, 

 available for clinical medicine. On account 

 of a temporary pulmonary affection, Traube 

 sent him to Italy where he stayed for some 

 time, an incident which left a mark upon Kro- 

 necker's future activities. The acquisition of 

 the knowledge and the use of the Italian lan- 



guage was unquestionably a factor in his fu- 

 ture intimate relations with the Italian physi- 

 ologists. He recovered his health and even 

 served in the Prussiari wars with Austria 

 and France. In the Pranco-Prussian war he 

 received the iron cross for bravery. In 1868 

 he entered Ludwig's celebrated " Physiologische 

 Anstalt zu Leipzig," where he remained until 

 1876, becoming assistant in 1871, and professor 

 extraordinarus in 1874. In 1877 he was called 

 to Berlin to become the head of the division of 

 experimental physiology in the Institute of 

 Physiology which had been recently organized 

 by du Bois-Eeymond. In 1884 he was called 

 to Berne, where he filled the chair of physiol- 

 ogy until the last day of his life. 



Kronecker's scientific activities extended 

 over more than half a century; his thesis ap- 

 peared 1863. But the investigation which 

 raised him to the rank of a first-class physiol- 

 ogist was his work on "fatigue and recovery 

 of striated muscles " published from Ludwig's 

 laboratory in 1872. The careful planning of 

 the experiments, the exactness and skill with 

 which they were executed and the sharp analy- 

 sis which permitted the derivation of general 

 laws put a classical stamp upon this piece of 

 work; its celebrated tracings were the start- 

 ing point for many future ergographic studies. 

 The later work during his Leipzig period was 

 mainly devoted to the cardiac muscle ; some of 

 the results found a permanent place in physiol- 

 ogy. I may mention here the development of 

 the " all or none " law ; the loss of irritability 

 of the cardiac muscle during systole (refractory 

 period, Marey) ; the importance of inorganic 

 salts for the heart beat (with Merunowitz and 

 others). Of his many investigations during 

 his Berlin period I should mention the studies 

 which led up to the use of transfusion as a 

 life-saving means (present-day writers do not 

 seem to know that Kronecker was the inventor 

 of this method) ; the extensive studies (with 

 his colaborers) on the physiology of degluti- 

 tion ; the discovery of a coordinating center in 

 the heart. I wish to record here the fact that 

 Kronecker had an essential share in the devel- 

 opment of the clinically important methods of 

 studying blood pressure in human beings. The 



