ELECTROMOTIVE ACTIOX IN XERVE 



similarity of electromotive reaction in the two cases proves 

 nothing as to qualitative equality of chemical process. Hering 

 points out that " we must hesitate, in view of the endless 

 variety of the different chemical processes by which electrical 

 currents are engendered, to affirm an equality of internal process 

 in the nerve from the similarity of electromotive reaction in 

 two nerve -fibres (more especially in those of which the excita- 

 tion produces very dissimilar central and peripheral reactions), 

 or in one and the same fibre under different conditions : or 

 to exclude the possibility that different kinds of internal altera- 

 tion may be transmitted within certain nerves, or even to 

 assume the same process for all nerves (with the single possible 

 exception of certain sensory nerves)." "Muscle, gland -cells, 

 plant cells, perhaps indeed all living substances, exhibit under 

 certain conditions an electrical reaction, which from its very 

 commencement presents a striking analogy with the electrical 

 reaction of nerve. Should we therefore " (continues Hering) 

 " conclude that the internal chemical processes which are the 

 cause of these manifestations are alike in all parts of the living 

 substance, or that when the same electrical effects occur in two 

 cases within the same substance the underlying chemical altera- 

 tions must necessarily be the same?" (Hering, 24, p. 19 ff.) 

 From this point of view it is, if surprising, at least intelligible 

 that the presumably assimilatory, cardiac inhibitory, vagus fibres, 

 the excitation of which produces a positive variation of the 

 muscle current, should, even as regards their galvanic reaction 

 to excitation, differ in no respect from other nerve-fibres. 



S. Fuchs (25) has recently communicated some interesting 

 observations upon the negative variation of centripetal nerves 

 during adequate excitation of their peripheral end-organs. The 

 Selachians, and notably the Torpedinidce, possess a special system 

 of canals beneath the skin, which partly open under the skin 

 (Lorenzinian ampullae and pectic tubes), and partly form blind 

 sacculffi (Savian bladders), but are always intimately connected 

 with the nervous system, and are undoubtedly sense-organs. In 

 Torpedo, the Lorenzinian ampullae are globular sacs divided into 

 four compartments by partition walls. These sacs are enclosed in 

 a special capsule, of which there are two pairs in Torpedo ; one 

 pair lies in the nose exactly in front of the eyes, and contains, 

 according to Leydig, about 100 ampulla? in the two capsules, the 



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