Physiology of Animals. 59 



formations of energy in the body, the problems of 

 animal heat and body-temperature, the dynamics of the 

 circulation, animal electricity, the mechanics of move- 

 ment, the optics of the eye, the acoustics of the ear, 

 and so on ; in short, the study of all those phenomena 

 associated with life which admit of being studied and 

 measured by the methods and instruments of experi- 

 mental physics. Perhaps it may be said that the whole 

 body of research in this direction is centred in the 

 doctrine of the conservation of energy which Joule and 

 Mayer established, and which was shown by Helmholtz 

 and others to hold true for the living organism as well 

 as for the dead engine. 



Among those who have welded the contact between 

 physics and physiology, and equally, per- Du Bo is- 

 haps, among those who have vindicated the Reymond. 

 biological standpoint in modern culture, Emil du Bois- 

 Reymond (1818-1896) ranks high. 



He was interesting personally as a man of versatile 

 genius, as a loyal German patriot of French descent, 

 and as one of the many who have reacted from Theology 

 to Science, doubtless to the benefit of both. After a 

 period of interest in geology he found himself, along 

 with Helmholtz and many other afterwards illustrious 

 workers, at the feet of Johannes Miiller, whose chair he 

 eventually filled. 



Taking up the clues which Galvani and Volta had 

 first handled about the end of the eighteenth century, 

 and which many had tried to use, Du Bois-Reymond 

 devoted his life to the study of the electromotor pheno- 

 mena associated with muscle and nerve. There are 

 electric currents in these tissues, and alterations in the 

 currents during functional activity. By working out 

 the intricate details of this thesis, now so familiar to 

 students of medicine; by the more general application 

 of physical methods to physiological problems; by 

 introducing ingenious instruments ; and by establishing 

 (after many years of sorry quarters) a truly wonderful 

 Physiological Institute, he did great service to physi- 

 ology. 



In spite of his lifelong devotion to one main problem, 



