SECT. 85.] MUSCULAR SYSTEM. 155 



attenuation of the fibres, till at length very small fibrils of o-ooi"' to 

 0*0015'" in diameter result. The divisions are for the most part dichoto- 

 mous or trichotomous, more rarely multiple ; yet Wagner once saw eight 

 branches. The terminal fibrils are pale, and simply contoured. They 

 never penetrate into the muscular fibres, but, after a short course, either lie 

 obliquely or transversely upon them, or continue for a considerable distance 

 parallel to them, in order, in both cases, to run out into a point, which is 

 often as fine as a fibril of connective tissue. All these relations may be well 

 seen in the mylo-hyoideus ( Wagner), and above all in a fine cutaneous muscle 

 of the thorax (Eeker), the distribution of the nerves in which has recently 

 been very minutely described by Reichert. Reichert found here, as in man, 

 that only a small part of the muscle is abundantly provided with nerves ; 

 whilst they are few in number in the remaining parts. The nervous trunk 

 supplying this muscle, which consists of 160 to 180 muscular fibres, has, 

 according to Reichert, 7 to 1 o tubules, and finally forms, by repeated division, 

 290 to 340 terminations, so that there is more than one termination for every 

 muscular fibre. 



§ 85. Chemical and Physical Relations of the Muscles. — Accord- 

 ing to JBibra, there are in 100 parts of fresh beef, 72*56 to 74*45 

 parts of water. The solid parts (25-55 to 27-44), in a man 59 

 years of age, consisted of a residue insoluble in boiling water, 

 alcohol and ether, 16 83 ; soluble albumen and colouring matter, 

 1-75; substance yielding gelatine, 1*92; extractive matter and 

 salts, 2-80 : fat, 4*24. The fat is chiefly derived from the blood, 

 the fat- cells in the muscles and the nerves ; in part also from 

 the muscular fibres themselves. The substance yielding gelatine 

 comes from the perimysium, a small part also from the vessels 

 aud the neurilemma; but not from the sarcolemma, which is still 

 to be seen in thoroughly boiled muscles. The inorganic salts 

 and the albumen come chiefly, perhaps, from the muscular fibres 

 themselves, whence also pre-eminently are derived the salts of 

 lactic, acetic, butyric and formic acids, found in the juice of 

 muscles by Liebig and Scherer, the free lactic acid, kreatin and 

 kreatinin, the sugar of muscles, or inosit and the colouring 

 matter ; which substances, including the last mentioned, have 

 their seat, partly in the fibrils themselves, partly, as is especially 

 the case with the albumen, in the intermediate connecting sub- 

 stance. The insoluble residue (16*83) ^ s f° r the m ost part due 

 to the muscular fibrils themselves, which, as we have seen above 

 (§ 29), are composed of a substance allied to fibrine. The sarco- 

 lemma offers greater resistance to alkalies and acids than the 

 fibrils, aud is more nearly related to the membrance propria; of 

 glands, the Avails of capillaries, and the cell-membranes of many 

 cells. The colouring matter of the muscles (and these themselves), 



