ELECTROMOTIVE PHENOMENA IN 



GLANDS. 



IN so many instances of physiological action has it been 

 demonstrated that there is a development of electro- 

 motive force, that the physiologist almost expects to find 

 an electrical expression of any essential vital phenomenon 

 under his consideration. 



In muscle and nerve, the story has been studied now 

 for upwards of a century, and the mass of our knowledge 

 of the processes underlying the development of electricity 

 in animal tissues, culled from these, the oldest sources, forms 

 the base upon which the theory of the subject mainly rests, 

 the standard to which the points of more recent discoveries 

 are frequently referred. 



What knowledge we have of the electrical events taking 

 place in secreting cells is, however, of fairly recent date, 

 and although the accumulation of facts is considerable, their 

 interpretation is as yet a matter of great difficulty. 



The glands of the frog's skin have all along been favourite 

 structures for the investigation of the matter, on account of 

 the great ease with which a nerve-skin preparation is 

 obtained, and it will be convenient to first sketch the facts 

 known regarding these organs. 



Emil du Bois-Reymond, in 1S51, in his endeavours to 

 demonstrate the existence of electrical currents in the 

 muscles of uninjured frogs, discovered that the skin of the 

 animal was itself a source of electromotive force, which was 

 altogether of too hicrh magnitude to be attributable to mere 

 differences in chemical reaction between the parts to which 

 the electrodes were applied. Finding that removal of the 

 surface layers containing the glands abolished the current, 

 and that the skins of fish, which he considered non-glandular, 

 gave no such current, he concluded that the glands of the skin 

 were a source of electromotive force with ingoing current. 1 



1 Throughout this article, the terms ingoing and outgoing applied to 

 gland currents have the following significance : Ingoing current means a 



