124 Obituary Notices of Fellows deceased. 



EMIL DU BOIS-KEYMOND. 18181896. 



" With intellectual leanings impelling me in almost equal degree in 

 various directions of natural knowledge, it has been my fate as an 

 investigator to devote my endeavours almost exclusively to a single 

 and, apparently, quite limited province. I was 22 years old when 

 Johannes Miiller set before me the question as to the nature of 

 Nobili's frog-current, and now, after the lapse of 34 years, I am still 

 searching for the answer to that question." 



Thus wrote du Bois-B-eymond in 1875, and the search was pursued 

 for yet another 20 years. 



Born in Berlin in 1818, educated partly in Berlin, partly in Neu- 

 chatel, he owed much to the foresight of his father, who, as du Bois 

 himself relates, "had the goodness, in spite of his slender means, not 

 to press his son into practical life, but enabled him to devote himself 

 to the study of animal electricity." 



At 22 years of age (1840), having completed his medical curriculum,, 

 be became Muller's assistant and embarked at once upon what proved 

 to be his life-work. At the end of his first seven years' service (1848) 

 the first volume of the " Untersuchungen iiber Thierische Elektiicitat 5r 

 was published ; in the next year the second volume appeared, breaking 

 off, however, in the middle of a sentence, of which the concluding 

 words did not see the light until 1884. The pause of 35 years is of 

 itself an eloquent commentary upon the care and patience of the 

 student, and it was a busy pause how busy we may best realise from 

 du Bois-Reymond's own apology and justification. 



" The multiplier with its double needle was soon completely dis- 

 placed by the reflecting galvanometer. Platinum electrodes in salt 

 solution gave way to amalgamated zinc in zinc sulphate ; albuminised 

 membranes to modelling clay. Unpolarisable electrodes made it 

 possible to map out lines of current and of potential in animal electro- 

 motors with greatly increased exactitude, and to apply exciting cur- 

 rents to the tissues with far less fear of fallacy. The dreaded 

 inequalities of action at the metallic ends of the multiplier, that cost 

 me such long hours of fruitless struggle, lost all their terror. Such 

 slight inequalities as were still encountered were annulled by a twig 

 of current ; and by the compensation method electromotive forces 

 came to be measured like cloth by the yard. Their exact numerical 

 measurement took the place of rough estimations of current-strength. 

 The aperiodic magnet not only facilitated galvanometric observations 

 to a degree that was hardly realised outside electro-physiological 

 laboratories, but actually brought within range many otherwise inac- 



