v ELECTROMOTIVE ACTION OF EPITHELIAL AND GLAND CELLS 487 



always retreats into the background. Yet this is by no 

 means to say that the contrary might not occur under other 

 conditions. The preceding statement refers only to lingual 

 preparations which exhibit the normal reaction, i.e. vigorous 

 entering mucosa current. It is also quite indifferent in what 

 manner the lead-off is effected. In the entire uninjured frog 

 we have either led off from the muscles of the leg and upper 

 lingual surface, or made use of the previously described prepara- 

 tion of the lower jaw, which is easily brought into connection 

 with the glossopharyngeal nerve, so that the experiments in 

 question are directly comparable with the former. The last- 

 named experiments made it possible to test the excitation of the 

 nerve on preparations of the tongue in which the entering rest 

 current has been weakened, or reversed, by treatment with 

 strong (O'S 1'5 / Q ) NaCl solution. As the nerve is not in- 

 jured by a short application of solutions of this concentration, 

 the excitation effects (manifestations) observed must principally 

 be referred to the changes undoubtedly present in the glandular 

 cells excited. In such cases we have frequently noted excitation 

 effects which correspond throughout with those described by 

 Hermann and Luchsinger, a strong positive effect being periodically 

 interrupted by a weaker negative. 



There is accordingly complete agreement in nearly every 

 point of electromotive action between direct and indirect excitation 

 of the lingual mucosa, another proof that in the methods of direct 

 excitation employed we are only dealing with effects which 

 originate in the mucosa. Another question, on the other hand, which 

 cannot be answered as certainly, is whether in the previous instances 

 direct and indirect excitation must not be regarded as identical, in 

 so far as only the nerves which are situated in the mucosa are 

 excited in the first case also. Some poison is required which, like 

 curare in striated muscle, will entirely abolish nerve action with- 

 out injuring the gland cells. Atropin at once suggests itself, 

 as having long been known to abolish the effect of excitation in 

 secretory nerves completely and permanently, in the most different 

 glands. Hermann and Luchsinger showed that it had the same 

 effect on the galvanic effects of excitation in the frog's tongue. 

 Both after direct dropping on to the tongue, and subcutaneous 

 injection, the strongest excitation of the nerve is ineffective, 

 although, as we have repeatedly ascertained, direct excitation 



