THE MUSCULAR SYSTEM. 287 



means of the rotation apparatus, of the muscle to be examined, 

 such, for instance, as the abdominal muscles and slender 

 muscles of the extremities in the Frog, the diaphragm and 

 cutaneous muscles of the smaller Mammalia, &c. Fur this 

 purpose the muscle must be placed upon a piece of looking- 

 glass, from a small space in the middle of which the metallic 

 coating has been removed. One of the conducting wires is 

 brought through an opening in the stage, or else affixed to it 

 so as to be immoveably in contact with one of the portions of 

 tinfoil. If the muscle now be viewed under a magnifying 

 power of 100 linear, whilst the second conducting wire is 

 brought in contact with the other portion of tinfuil, the 

 moment the circuit is completed, its fibres will be seen to 

 contract in a rectilinear direction, and at the same time to 

 become thicker, whilst the transverse striae are more closely 

 approximated (vide fig. 109, which represents both a contracted 

 and an extended muscle). The muscular fibres remain in this 

 condition so long as the galvanic influence is kept up, whilst 

 when the circuit is broken they elongate themselves as rapidly 

 as they contracted, and present zigzag flexures, when the 

 muscle is lying free, but not when it is stretched by small 

 weights attached to it bv threads. From this it is evident, 

 that if zigzag flexures take place during life, which is not 

 yet known to occur, they can only arise when muscles in the 

 quiescent condition are not in a state of tension ; as, for 

 instance, in the case of a flexor muscle, which has come into a 

 state of rest after it has produced its full effect upon the limb. 

 The sarcolemma is readily seen in the muscles of Amphibia and 

 Fishes, especially in specimens preserved in spirit, in which it 

 frequently, but for the most part in places, appears at a distance 

 from the fibrils. In the higher animais and in man, it is 

 occasionally seen when the fasciculi are teased out ; and also in 

 macerated and boiled muscles, and on the addition of acetic 

 acid or alkalies. For this purpose I would especially recom- 

 mend caustic soda, which in many cases renders the contents of 

 the muscular tubules so fluid, that they escape in a continuous 

 stream together with the nuclei, when the sheaths come very 

 clearly into view. In no case, however, is the sarcolemma, in 

 man, more beautifully exhibited than it is, in softened, atrophied 

 muscles which have undergone fatty or other degeneration ; 



