210 



rilYSIiM.ni.Y <>! MUSCLES AND NKKViS. 



If (lie nerve {' the mii-ele /> is tin 'ii irritated, cither liy 

 closing or by opening ;i current , by an inductive shock, by 

 x-i.-sion, by pressure, or in any other way, the muscle A 

 \> oh<er\ed In jul>ate also. 'J'liis is called .svr, >//,/- 

 ary pulsation. The explanation is easy. The muscle- 

 ctirren! from />' during its pulsation suffered a ne^ati\e 

 variation. This variation took place also in that por- 

 tion of the current which passed through the applied 

 nerve; and, as every nerve is, irritated by sudden change 



C 



Jf 



FlO. .">7 \ 58. S-l - iM)AKY 



in the strength of the current, the re-ult was a secon- 

 dary pulsation. 



A variation of this experiment is very interesting. 

 The heart of a fn>Lr continues to bent for some time 

 after it has been extracted from the bodv. If the nerve 

 of a nniM-lr i- placed on this heart so as to touch its 

 base and point, the muscle pulsates at every beat of 

 tile heart. In this case, the heart-muscle affords the 

 muscle-current, the negative variat ion of which irritates 

 the applied nerve and cau-e- >rcondary pulsation. 



']m]s;ill<m uilhiiut in. 'tills' (/tirl;ini<i nlun- Mitnllf) \\hich l::is 

 -allied .cl.'l.riiy I'l'-ni the \\ritin-.s ..!' Vnlta, HuiiilMil.lt, uiul 





