500 ELECTRO-PHYSIOLOGY CHAP 



ab initio concerned in its production. In the second, no trace of 

 secretion even with the magnifying lens was to be discovered 

 during excitation of the dry surface of the skin, which is so easy 

 to detect under normal circumstances. The result remained the 

 same when the skin surface was moistened with water, or 

 0*5 / Q salt solution. Hermann subsequently applied the same 

 process of secretion to the interpretation of the contrary effect 

 the negative variation in the entering skin and lingual rest 

 current (frog). He starts with the assumption that the skin 

 glands are normally " nearly closed to the external surface, i.e. 

 have no external galvanic relation." If during excitation a 

 sudden compression of the liquid contents sets up a deflection of 

 the ingoing current in the glandular epithelium, then under the 

 further presumption of a homodromous, electromotive activity of 

 the remaining epithelium "the relation of E.M.F. between 

 glandular skin and epithelium " determines the character of the 

 phenomena of excitation. 



If the first is greater, a positive increment of the rest current 

 appears, an "ingoing secretion current." "If the E.M.F. of 

 the gland epithelium, on the contrary, is less than that of the 

 skin epithelium, as must be presumed in the resting state of the 

 glands, the mere mechanical process of secretion will produce a 

 diminution of the rest current, followed however by augmentation, 

 so soon as the excitation of the nerve incites the cells to 

 secretory activity." Notwithstanding Hermann's recent protest 

 (82), we continue to hold this explanation fallacious, and are still 

 of opinion that the conditions of leading off are similar to those 

 in the frog's tongue. 



The electromotive action of the mucosa of the stomach claims 

 attention both on theoretical grounds, and in regard to the 

 disputed question as to the existence of special secretory nerves 

 to the glands. We found above, as first stated by Eosenthal (73), 

 that the mucous coat of the frog's stomach had normally the 

 same electromotive action as the outer skin of fishes and naked 

 amphibia, i.e. on leading off from the free internal surface and 

 muscular coat a powerful ingoing current is exhibited, which 

 Eosenthal does not hesitate to connect with the mucous glands. 

 Yet in view of the facts discussed above we must admit another 

 possibility, viz. that the whole surface epithelium may consist of 

 elements, which are to be regarded as unicellular mucous glands 



