476 ELECTRO-PHYSIOLOGY CHAP. 



the entering " rest current " of the throat mucosa as a " secretion 

 current." The lingual current is usually found at a certain 

 stage of pilocarpin poisoning (two hours after injection of 

 1 cc. of 2 % solution of pilocarp. muriat.) to be extremely 

 vigorous, and the same is true, according to our experiences, of 

 the throat and cloacal currents. The deflection is normally so 

 strong that the scale flies off the field. 



Since there appears from the above experiments to be no pro- 

 portion between vigour of ciliary movements and intensity of 

 electromotive action, while the observations of Engelmann, which 

 seem to indicate such a relation, are capable of quite another in- 

 terpretation, we have so far failed to discover any reason why the 

 entering current of the mucosa should be referred to any other 

 cause than the homodromous lingual or cloacal currents, unless in 

 the sequel there proves to be similar electromotive action on 

 the part of a membrane consisting only of ciliated cells. We 

 have seen that the uniformity of electromotive reaction in 

 the two preparations in question, and the lingual mucosa, is 

 almost perfect. This is true not only of the inconstancy of the 

 current, but also of the effects of cooling and excitation. In 

 nearly every case in which the E.M.F. has reached a certain 

 height, oscillations of the magnet may be observed, from which 

 we may conclude the presence of heterodromous forces, the sum 

 of which corresponds with the momentary deflection. And 

 jtist as this magnitude alters with time at one and the same 

 point, it may vary at different points of the mucosa at the same 

 moment. As a rule the entering current of the cloacal mucosa 

 is far more vigorous than that of the throat as might be 

 expected a priori if the unicellular glands (goblet cells) are to 

 be held responsible for it. 



Engelmann had observed that this current is weakened by 

 cooling, but it escaped his notice that under uniform conditions 

 a total reversal may be possible. In fact, nothing is easier than 

 to convince oneself that by laying a preparation of the upper 

 jaw in 0*5 % NaCl solution cooled to zero, the strongest 

 entering current may be made to disappear in the shortest pos- 

 sible time (5-10 minutes). Immersion in warmed salt 

 solution (about 25-30 C.) calls back the normal current 

 almost instantaneously. In order to produce an "outgoing" 

 current of any considerable proportions, it is, as a rule, necessary 



