xvr.] 



STRIPED OR STRIATED MUSCLE. 



195 



water to cool gradually (Ranrier\ It will now be found that the 

 fibres of any muscle can be dissociated with great ease ; the muscles 

 to be preserved in 70 per cent, alcohol until they are required. 

 By careful manipulation very long fibres may be isolated from the 

 sartorius. These muscular fibres exhibit the ordinary characters 

 of striped muscle. This is by far the easiest method of obtaining 

 isolated fibres. 



(ii.) Place small pieces of a fresh muscle in the following mixture. 

 Nitric acid saturated with potassic chlorate. There must be crystals 

 of the latter in the fluid. The tube or , 

 vessel is speedily filled with yellow 'i^3Sl 

 nitrous fumes. It is usually advised ^3^-' : 

 to leave the muscle several hours in 

 this fluid. I find, however, if this be 

 done, that the muscle is dissolved. 

 Half an hour is usually sufficient. 

 With glass rods remove the now 

 softened orange-coloured muscle, and 

 place it in water. It becomes whitish. 

 Shake it in a tube with water. The 

 fibres fall asunder quite readily, and 

 after having all the acid removed by 

 prolonged washing, they can be stained 

 and mounted. 



4. Fibrillse of a Muscular Fibre 

 (H). Place a frog's or mammal's 

 muscle in water (two hours), and after- 

 wards in dilute alcohol for twenty-four 

 hours. Tease a small fragment of the 

 now softened muscle in glycerine, or 

 tease a fresh muscle of a calf in white 

 of egg. If a fibre be split up, bundles 

 of fibrils may be seen as in fig. 168. 



Select a fibre, and note that at its 

 free end it splits up longitudinally into 

 a large number of very fine fibrils or fibrillae, each of which is 

 transversely striated like the original muscular fibre. Much larger 

 fibrils are obtained from the muscles of insects, e.g., Hydrophilus or 

 Dytiscus (fig. 171). 



5. Muscle-Discs (H). The usual directions for obtaining these 

 are to place dead muscle for several days in dilute (.2 percent.) 

 hydrochloric acid. The, muscular fibre then cleaves transversely. 

 I have not found this to be a very satisfactory method. A much 

 better plan is to place small pieces of the muscle in a saturated 

 solution of ammonium carbonate for several hours. 



FIG. 



Lped 



lar Fibre of a Calf, teased in 

 white of egg, and showing iso- 

 lated bundles of fibrils, x 200. 



