:V_> rilY.-InI.o.,Y <>F MTSCLES ANI> NKKVi 



All el.-ctric em-rent from the hat t ery it self is also 

 capable of acting as an irritanl 'n muscle. lfthepoi,-> 



of tin- 1 lattery are c< >nnected with the muscle, a con-taut 

 current pa.-.-es through it. If OIK- of the connecting 

 \\ires consists of t\vo parts, a capsule filled with quick- 

 silver may l>e inserted between the cut ends. One end 

 of the wire must be allowed to remain immersed in the 

 quicksilver ; the other end must be bent into the form 

 A a hunk st.) as to allow it to be easily immersed in, ;md 

 again withdrawn from, the quicksiher. This make-, 

 it easy to close the current \\ithin the mu-cle, and 

 to interrupt it again at pleasure. At the moment 

 at which the current is dosed, a pulsation is observed 

 entirely similar to that which would be produced hy 

 an electric shock. The mii-cle contracts, and the disc 

 is jerked upward and then falls a-ain. But it does 

 not return quite to its original portion; it remains 

 somewhat raised, thus showing that the muscle is now 

 continuously contracted; and this contraction lasts a- 

 long as the current passes uninterruptedly through the 

 muscle. 



If the current is interrupted, a pulsation which 

 jerks the lever up\\;.rd i- sometimes but not always 

 oh.-ervablc ; the muscle then, however, resumes its 

 original length, which it retains until it is irritated 



-> 

 anew. 



2. The.-e experiments show that muscle exhihits 

 two forms of contract ion : the one, which we ealh d pul- 

 sat ion, is of short durat ion ; the other, \\hicli is produced 

 by a con-taut electric current, endures longer. Tin's 

 more enduring form of con! ract i..n may, moreover, he 

 yet more conveniently produeed hy allou ing an irritant 

 as in itself would only prodiiee a single pukiti.ui 



