GLANDS AND ELECTRIC ORGANS. 243 



but magnetic rod N l S l (fig. 66). At the moment at 

 which the magnet NS is brought near, the magnetism 

 of N l Si becomes weaker, ceases entirely, or is even 



FIG. G6. MAGNETIC INDUCTION. 



reversed. The same process of magnetic induction is 

 concerned in both cases. The only difference is that in 

 one case the induction seizes on an iron rod the mole- 

 cular magnets of which are irregularly arranged, and 

 which therefore appears non-magnetic; while in the 

 second case the iron rod is in itself magnetic. So that 

 in one case magnetism is evoked by induction, in the 

 other, magnetism which was already present is weak- 

 ened ; but the induction is the same in both cases. In 

 just the same way electric tensions are induced in the 

 electric plate by the influence of the nerves, while the 

 tensions present in the muscle are weakened ; but the 

 process in the electric plate and in the muscle is the 

 same. 



We have now only to say a few words about the 

 glands. The phenomena in these are, so far as we can 

 infer from the few known facts, so entirely like those in 

 muscles, that it is only necessary to transfer the expla- 

 nation which we have given in the case of the muscles 

 to the glands. In each gland-element electric forces 

 are present which make the base of the gland positive, 

 the mouth-opening negative. When the gland becomes 

 active, these differences in tension become less. There 

 is no occasion to speculate as to how far this affects the 

 process of secretion, as it could not further explain the 

 process. 



