302 ELECTRO-PHYSIOLOGY CHAP. 



dromons, electromotive activity occurs at the end of the closure of 

 the polarising current. Between the two leading-off electrodes, 

 again (as in the phasic currents of action), there are two 

 successive, opposite, and unequal phases of current, the first and 

 stronger of which is homodromous with, the second on the other 

 hand heterodromous to, the polarising current. This last phase 

 does not here imply that the undulatory process moving forward 

 with a rapidity of 20-65 metres per sec. which on reaching the 

 first leading-off electrode produces the first phase gives rise to an 

 opposite phase at the second contact (when it is simultaneously 

 extinguished or greatly diminished at the first) ; hut it is due to a 

 heterodromous current arising at break of the polarising current, in 

 the intrapolar tract of the core-conductor. " Shortly expressed, 

 the second phase is nothing else than the comparatively retarded 

 state into which the core-conductor is thrown by polarisation, in 

 consequence of the rapid succession of momentary closures of the 

 polarising current. The first phase, however, is the undulatory 

 action of each single momentary closure, superposed upon this con- 

 dition. It appears in complete integrity, when the two opposite 

 polarisations of the wire core do not neutralise each other, or 

 when one polarisation only is present, so that a bipolar current is 

 impossible " (Hermann). 



While Hermann is very cautious in accepting the possible 

 bearings of these remarkable but theoretically insufficiently - ex- 

 plained phenomena upon the transmission of excitation in the 

 nerve, and admits that there may be only plausible analogies, 

 Boruttau (20) has recently adopted the extreme physical stand- 

 point. He finds that, on leading in the alternating currents of an 

 induction apparatus to a core composed of platinum or palladium 

 wire in 0'6 per cent saline, by means of a rheotome, galvanic un- 

 dulations are manifested, due to the rapid transmission (over 100 

 metres per sec.) of a negative phase to a considerable distance, and 

 corresponding throughout with the phasic currents of action 

 (inter alia, as regards effect of temperature upon rate of trans- 

 mission). As we have stated, he views the negative variation 

 also as no more than an undulatory katelectrotonus. By employ- 

 ing very long core-models, consisting of many glass tubes placed 

 together, by which the distance between traversed and led-off 

 tracts could be increased to 4 metres, Boruttau observed the 

 undulatory transmission of negativity, and this alone, with great 



