v ELECTROMOTIVE ACTION OF EPITHELIAL AND GLAND CELLS 513 



with many variations, as regards the succession of the two 

 phases. While in the cloaca with a moderately strong entering 

 mucosa current, a positive variation usually precedes the stronger 

 negative effect as a fore-swing, in the mucosa of the throat, under 

 the same conditions, the negative is very frequently interrupted 

 by a positive swing. It is clear that even with complete equality 

 of the two current -generating processes (when currents that" 

 can be led off externally are altogether wanting) the possibility 

 of a " secretion current " is not excluded, provided the one or 

 other process is preponderant. Since, in view of the experimental 

 reactions under discussion, this is rather to be expected of the 

 " negative " than of the " positive " process, it is intelligible that 

 positive deflections in the direction of an ingoing current should be 

 visible where the excitation is not too strong. More frequently, 

 however, all galvanic effects of excitation are wanting, from 

 which it must not, of course, be concluded that the secretory 

 process excited by the current is absent, but merely that a 

 particular, physical symptom of the same has in this case not 

 found expression. While, finally, it seems almost self-evident 

 from the previous argument that where there is a " reversed " 

 outgoing current in consequence of excitation, there should also 

 be, in an overwhelming majority of cases, deflections of the 

 magnet in the direction of an ingoing current. At all events 

 this is the case almost without exception with weaker excitation, 

 while stronger stimuli, even under these conditions, may still 

 produce a positive variation. 



The electromotive action of the skin glands (sweat glands) of 

 mammals and of man is far less exactly determined than in the 

 uni- and niulticellular mucous glands. Ever since du Bois-Eey- 

 mond exhibited his famous experiment (at first referred to the 

 action current of the muscles) on man, in which the lead-off is 

 from both hands or both feet, symmetrically, after which voluntary 

 contraction of one arm, or one leg, deflects the magnet of the 

 multiplier, it was conjectured that this might indicate the 

 development of an entering skin current in consequence of 

 excitation. After Hermann's observations it must be admitted 

 that the action current from the muscles plays no part in it, 

 while if any doubt could still remain on this point, it must finally 

 give way before the experiments of Hermann and Luchsinger on 

 the secretory currents of the cat's skin. As we pointed out in 



2 L 



