RESPONSE OF DIGESTIVE ORGANS 337 



motile responses which they occasion. But in glandular 

 organs, they become possessed of much greater significance, 

 since they constitute the main function of such structures. 



Electrical responses, in every way analogous to those 

 which have been described, are obtained from the glandular 

 surfaces of digestive organs. That is to say, the glandular 

 surface when fresh exhibits responsive galvanometric nega- 

 tivity on excitation. In Drosera, for example, under these 

 conditions secretion is seen to take place. Thus the negative 

 phase of response, in this as in the case of Mimosa^ is asso- 

 ciated with expulsion of fluid or secretion. After continuous 

 stimulation, again, the responsive phase here, as in Mimosa, is 

 found to be reversed to positive, indicative, as there is every 

 reason to believe, of absorption. From a consideration of 

 the functions of the digestive organ, we should be prepared, 

 as already pointed out, to expect the occurrence of two 

 alternating processes. In the fresh state, ingestion of food, 

 acting as a stimulus, would naturally induce excitatory 

 secretion ; and this excitatory secretion must be followed 

 later by the absorption of dissolved food. These alternating 

 phases of secretion and absorption indubitably occur. We 

 shall also find, in the electrical response-records, a phasic alter- 

 nation of negative and positive under appropriate conditions. 



We have seen that there is a continuity between the 

 different reactions of non-glandular and glandular tissues. We 

 have also seen that, as in the one case, so too in the other, 

 a phasic change takes place from negative to positive. In the 

 digestive organ, however, we have to deal mainly with the 

 fluctuations of fluids secretion and absorption and the 

 attendant electrical variations, which consist of two opposite 

 phases, positive and negative. As far as I have found it 

 possible to test the matter experimentally, it has invariably 

 been the case that the negative electrical phase was associated 

 with secretion ; and everything points to the probability that 

 the converse of this the association, namely, of^ the positive 

 electrical phase with the process of absorption holds equally 

 good. 



