360 ELECTRO-PHYSIOLOGY CHAP. 



electrical character of the discharge) of all these more or less 

 hardy speculations is best seen in the fact that, even in 1829, 

 Humphry Davy (whose brother, John Davy, at his instigation, 

 made extensive researches on Torpedo at Malta), expressed doubts 

 as to whether the electricity of the electrical fishes were really 

 identical with ordinary electricity ; while Faraday (who had the 

 good fortune to be one of the first who investigated that most 

 powerful of all electrical fishes, the South American eel, with the 

 best physical aids that Europe could supply) was unable a few 

 years later to procure from the discharge of the gymnotus the eight 

 effects which he laid down as essential to the identity of all 

 electricity (viz. sparking, thermic action, attraction and repulsion, 

 deflection of magnetic needle, magnetisation of steel rod, hydro- 

 lysis, conduction through hot air, physiological action). At a 

 later period, one blank only remained, failure of conductivity 

 through hot air. 



It is to du Bois-Eeymond that we owe the fundamentals of 

 a scientific physiology of electrical fishes, founded no less upon 

 theoretical considerations than upon sound experimental investiga- 

 tion. His data have been amplified by later workers, and the 

 main points, at least, may now be taken as established. 



Since the more recent contributions to the subject are only 

 intelligible if the structure and finer relations of the organs have 

 been mastered, it is, in the first place, advisable to give some 

 detailed account of these, taking the Torpedinidce as the best 

 known representatives of the group ; their structural relations being 

 the simplest and most obvious. Fig. 256 a represents half the 

 dorsal aspect of Torpedo marmorata, after removing the skin. On 

 either side of the head and branchial sacs lies a kidney-shaped 

 organ, running right through the highly -flattened, broad body, 

 from dorsal to ventral surface. From the superficial aspect these 

 resemble a honeycomb, consisting of irregular 5- to 6 -sided 

 prismatic columns in juxtaposition. A section vertical to the 

 plane of the body shows that the columns decrease in height from 

 within outwards. They are separated by partition-walls of con- 

 nective tissue, and in fresh preparations resemble, both in 

 appearance and in consistency, a grayish-red, semi-transparent 



jelly. 



The finer structure can be examined both in longitudinal 

 sections, parallel with the axis of the columns, and from the super- 



