334 COMPARATIVE ELECTRO-PHYSIOLOGY 



mechanical irritation of which would contribute to the 

 negativity of the mucous lining. 



Finding, then, that it would be impossible to obtain the 

 natural current, in a stomach which had to be cut open, I 

 next tur.ned my attention to stomachs which are naturally 

 open. These are seen in the upper concave surface of the 

 leaf of Drosera, for instance, which is provided with glandular 

 tentacles. I here made electrical connections with the upper 

 and lower surfaces respectively. But the tentacles excited by 

 the contact of the electrode bent and clasped it round, an 

 excitation which was seen in the galvanometer as negativity 

 of that surface. From this may be gauged the difficulties 

 which attend the observation of the true natural current of 

 rest in such an excitable organ as the stomach. The 

 demonstration, however, of the galvanometric positivity of 

 the snail's foot, and of the inner glandular surface of the 

 carpel of Dillenia indica, lead to a strong presumption in 

 favour of the true resting-current in the stomach being from 

 the non-mucous layers to the mucous. 



Having thus seen the difficulties imposed by the high 

 motile excitability of the tentacles of Drosera, I next turned 

 my attention to other specimens. We have seen that there 

 is a secretion of fluid at the lower end of the hollow interior 

 of the peduncle of Uriclis lily, and that the secreting inner 

 layer is here galvanometrically positive in a state of rest. 

 As this tube, however, is closed, it cannot be regarded as 

 subserving the absorption of food-material. But the same 

 limitation does not apply to those modified foliar structures, 

 the pitchers of Nepenthe l (fig. 200). These, as is well known, 

 are open. They have a histological differentiation, moreover, 

 of their lining membrane, actual glands being present 

 (figs. 20 1, 202), which are admitted to be comparable to those 

 of the animal digestive organ, though of a much simpler type. 

 A fluid is secreted by these glands, and insects entrapped in 

 the pitcher are in it dissolved or decomposed. The products 



1 I have to thank the authorities of the Botanical Garden, Sibpur, for 

 supplying me with these valuable specimens. 



