14 



Mr. G. J. Romanes on the 



[May 4, 



as well as does section of the nerve in the muscle. Moreover the higher 

 up the nerve is cut, the less is the degree in which these characteristic 

 alterations occur, until, if the section be made at about the origin of the 

 femur or one third of its length lower down, no trace of these alterations 

 can be detected. 



(6) Stimulating the sciatic nerve with acids, alkalies, &c., and warming 

 it has the same sort of eifects as cutting. 



(c) Throwing the end of the sciatic nearest the gastrocnemius into 

 kathelectrotonus has a well-marked effect of the same kind ; while throw- 

 ing the same part into anelectrotonus has the opposite effect, though 

 not in so strongly marked a degree. 



id) Severe galvanic tetanization of the gastrocnemius is frequently 

 followed by an increase of sensitiveness to the descending break nearly 

 as remarkable as that which follows cutting. As this effect does not seem 

 to occur in well-curarized muscles, I conclude that it must be due to an 

 increase in the excitability of the intramuscular nervous elements through 

 injury. 



§ 5. Another method which I employed to test the effects of nerve- 

 section on excitability was one which, in the first instance, I fell upon 

 accidentally. It consisted in joining up the non-polarizable electrodes 

 with a continuous bridge of clay made perfectly flat on its upper surface. 

 Care being taken to keep this surface uniformly moist, the sciatic nerve 

 in a nerve-muscle preparation was laid upon it ; so that when the current 

 passed through the clay bridge a portion of it also passed through the 

 sciatic nerve, thereby stimulating the attached muscle. The advantage 

 of this method consists in the facility with which different parts of the 

 nerve-length may be stimulated to the exclusion of other parts. By a 

 curious coincidence, Prof. Rutherford appears to have been working at 

 this subject at about the same time as myself, though quite independently 

 of me. It was only a few days ago that I became aware of this fact by 

 observing an article in this month's Number of the ' Journal of Anatomy 

 and Physiology,' in which Prof. Rutherford states his methods and results. 

 As nearly all the latter agree in every particular with those which I 

 obtained, I am now relieved from the necessity of detailing them. It is 

 desirable, however, to state that, viewed in the light of my other experi- 

 ments, these results amount to this : — When a few millimetres of nerve- 

 length, including the extreme nerve-section, rested on the clay, a much less 

 strength of current was required to produce the breaking contraction in 

 the muscle than when any other portion of the nerve of equal length was 

 allowed to rest on the clay. That is, in Prof. Rutherford's words, " the 

 striking fact ^ hoivev'er^ is that luithout altering the strength of the current 

 all the phenomena of Pfliiger's law could be obtained by transmitting it 

 through a central, middle, or peripheral portion of nerv^e, at one time in 

 an ascending, at another time in a descending direction." 



It may be worth while to state, as showing the astonishing excitability 



