'I'lio electrical phenomena accompanying Becretion. II!) 



effect more or less marked which is either positive! or negative, i.e. the 

 galvanometer- needle cither docs not return completely to zero or 

 passes the /ero and takes up a position on the other side: although 

 it may return exactly to the zero after the lapse of some minutes. 

 These temporary changes are but rarely absent, whereas the perma- 

 nent effects mentioned above although more pronounced are less fre- 

 quent. 3) Atropine even when given in moderate doses causes a di- 

 minution in the current of rest. 



We conclude therefore that not only is the current of rest largely 

 glandular in its origin, but that the variations observed in it are also 

 due to glandular activity, and not to any great extent to the changes 

 (drying etc.) of muscles exposed in the wound. Moreover in our later 

 experiments, where one electrode was placed on the cutaneous surface, 

 and one near the hilus of the gland in such a manner that the whole 

 gland was situated between the electrodes, the electrical changes pro- 

 duced by dying muscle would not so readily affect the galvanometric 

 deflections as in the earlier experiments. 



Besides the variations above noticed the current of rest during a 

 prolonged experiment usually increases at first, and then gradually 

 diminishes in amount. 



As we have already remarked the current of rest is fairly con- 

 stant in its sign, i. e. the hilus is positive to the outer surface, and 

 this also appears to be true of the parotid; i. e. the part of the gland 

 where the duct issues is positive to the remainder of the organ. 



The current of rest observed by the above method of leading off 

 is therefore probably an index of the differences of potential existing 

 in the gland. No doubt, from the shape of the alveoli, compensation 

 occurs to a large extent and this still further complicates the question 

 as to the cause of the difference of potential. On Hermann's „alteration- 

 theory" we might perhaps expect that the part of each cell next the 

 basement membrane (as being the more protoplasmic) would be posi- 

 tive to the part next the lumen. On the other hand it is possible 

 that the living cell is iso- electrical, and that the current of rest is 

 due to the difference of potential between the cell and its surroundings. 

 Further, as long as the gland is in a physiological condition, fluid is 

 continually passing through the basement membrane from the blood- 



