264 



GENERAL PHYSIOLOGY 



of vital force, upon a clear, exact foundation by creating for the 

 first time sure and comprehensive methods of research. In the 

 beginning, for evident reasons, only the muscles and nerves of the 

 frog served as objects of experiment; but soon du Bois-Reymond 

 brought into the range of his studies the interesting phenomena 

 of the electrical fishes. And numerous inquirers, such as H. Munk, 

 Hermann, Engelmann, Bernstein, and most recently Biedermann 

 ('95), investigated the electrical phenomena of plants and 

 various animal tissues. We are indebted to the researches of 

 Hermann for the key to an understanding of the electrical 



U 



FIG. 118. A, Simple arrangement for the production of a galvanic current. Zn, Zinc ; Cu, copper ; 

 the two joined below by a moist thread. The arrows indicate the direction of the current. 

 B, Simplest form of a galvanic element. Two metal strips (copper and zinc) dip into a liquid 

 and are joined together by a metal at their free ends. The current goes in the direction of 

 the arrow. 



phenomena of living substance. But it is due indisputably to 

 the fundamental labours of du Bois-Reymond that the science of 

 animal electricity has become one of the best-known branches of 

 physiology. 



The simplest method of obtaining a galvanic current, as is 

 well known, is that of soldering together at one end two strips 

 of different metals, e.g., copper and zinc, and bringing their free 

 ends into contact with a moist conductor, e.g., a moist thread 

 (Fig. 118, A). At the moment when the free ends of the metals 

 are joined by the conductor, an electric current begins to 

 flow in the closed circuit, passing from the zinc through the 

 conductor to the copper and from the copper through the 



