164 



MUSCULAR SYSTEM. 



[sect. 87. 





Fig. 74. 



by Ed Weber's method, which consists in galvanising, by means of the ro- 

 tation-apparatus, the muscle to be examined, such as the abdominal muscles 



and thin muscles of the extremities of the 

 frog, cutaneous muscles, the diaphragm of 

 small mammalia, etc. For this purpose, the 

 muscle must be placed upon a slip of looking- 

 glass, from the middle of which the metallic 

 coating has been removed for a small extent ; 

 and while one electrode is kept in connexion 

 with the metallic surface at one end of the 

 muscle, the other electrode is applied to the 

 metallic covering at the other end, and the 

 effect watched with the microscope. 



The sarcolemma can be readily demon- 

 strated in the muscles of amphibia and fish, 

 airSSffiZ! ^i'tretcSSt particularly in those preserved in spirit, in 

 and thin, with broad distant strife, b. w hich it is separated from the fibrils at va- 



The same not extended, thicker, and with . T^rr^f animals it is 



narrower, cinseiy approximated striae, nous points. In the higher animals, n is 

 Magnified 350 times. occasionally seen on teasing out the fibres ; 



further in fibres which have been macerated or boiled, and also on the ad- 

 dition of acetic acid and alkalies. I can especially recommend caustic soda 

 for this purpose, which, in many cases, renders the contents of the muscular 

 tubes so fluid, that they flow out, together with the nuclei, in a continuous 

 stream, and then the sheaths come very distinctly into view. But the sheaths 

 are nowhere more beautifully seen in human muscles than m such as are 

 softened, atrophied, affected with fatty or other species of degeneration; 

 and the more so, indeed, the more advanced and decided is the degeneration 



of the fibrils. 



In fresh muscles, the muscular fibrils may always be seen in transverse 

 sections (amphibia), and in the thoracic muscles of .insects ; most beautifully 

 in beetles (Aubert). They may also be seen elsewhere, but only now and 

 then and in favourable circumstances. They are readily isolated in prepara- 

 tions' preserved in alcohol, especially in the perennibranchiata (siredon, 

 proteus, etc.), by treatment with chromic acid (Hannover), by maceration for 

 from eight to twenty-one days at a temperature of 1° to 8° R. in water, to 

 which some corrosive sublimate has been added, to prevent putrefaction 

 (Schwann) ; maceration, also, in saliva (Henle) allows of then- being readily 

 demonstrated ; whilst, according to Frerichs, in the stomach, the fasciculi 

 break up into Bowman's discs, or at least break in the transverse direction ; 

 and this, according to Lehmann, also takes place by maceration in concentrated 

 nitric and hydrochloric acids, in nitrate of the protoxide of mercury (which, 

 after it has acted for a time, colours the contents of the fibres red, but not 

 the sarcolemma), and in carbonate of potash. The nuclei of the muscular 

 fibres can be best studied on the addition of acetic acid ; they may be isolated 

 by caustic soda (see above), and they swell up under the operation of potash 

 (Bonders) Respecting the action of various re-agents upon the muscular 

 elements the treatises of Donders (Holland. Beitrage), Paulsen (Observ. 

 Microchem, Dorp, 1849), and Lehmann (Phys. Chem., Bd. iii.), may be con- 

 sulted. The vessels of the muscles are studied in thin, fresh muscles, and m 

 injected preparations ; the nerves maybe seen in the smallest human muscles, 



