806 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



becomes continuous with the sarcolemma, and the white substance of 

 Schwann ; whilst the axis-cylinder, dipping in amongst the fibrillre, termi- 

 nates in a nerve-plate or disk, which melts by imperceptible gradations into 

 the tissue of the muscle itself. Cohnheirn, 1 whilst agreeing with Kiihne in 

 admitting the penetration of the sarcolerama by the nerve-fibres, represents 

 these as branching and dividing to a considerable extent. Kolliker, and 

 Beale and Krause, 2 on the other hand, deny the penetration of the sarco- 

 lemma by the ultimate branches of the motor nerves, the two former ob- 

 servers describing them as forming a plexus, composed of pale fibres of 

 extraordinary tenuity ( T oBoDT tn ofau inch), intermingled with many nuclei 

 lying on and ramifying over the fibres. Mayo describes a similar plexus 

 within the sarcolemma, whilst Krause admits the plate, but believes it to be 

 outside the sarcolemma. The three accompanying drawings will render the 

 views of Kiihne, Cohnheim, and Beale intelligible. The proportion of nerve- 

 fibres to muscular fibres varies considerably. 3 Tergast finds in the ocular 

 muscles of the Sheep, that there is one nerve-fibre to about 6 or 7 muscular 

 fibres. In the ocular muscles of Man, there are about 3 nerve to 7 muscu- 

 lar fibres. In the biceps of a young Dog there is one nerve-fibre to 83 

 muscular fibres ; in the sartorius of the same animal 1 to 40-60. In the 

 cutaneous pectoral of the Frog, the proportion is 1 : 23-27 (Reichert) ; in 

 the abductor digiti quinti pedis 1:40; in the sartorius 1:16^; in the 

 ocular muscles of the same animal, 1 : 10. In the caudal muscles of the 

 Mouse, 1 : 28-29. 



FIG. 289. 



Muscular Fibre, with termination of Motor nerve, from the Gastrocnemius of the Rana esculenta : a, 

 terminal pencil of a dark-bordertd nerve-fibre; b, intra-muscular naked axis-cylinder; c, nucleus of 

 the iicuriK-nima; <?, clavate extremities of the nerve; e, spaces of the muscle-nuclei;/, terminal knob 

 of nerve, with central fibre and vesicular dilatation of the nerve. (After Cohnheim.) 



658. Chemical Composition of Muscle. The muscles of cold-blooded ani- 

 mals are well adapted for chemical investigation on account of the slowness 

 with which they undergo change. If the muscles of such an animal, after 

 the removal of all blood from the tissue by the injection of a very weak 

 solution of common salt, be subjected to pressure, a neutral or weakly alka- 

 line fluid is obtained, termed " muscle-plasma," which soon undergoes spon- 

 taneous coagulation, and separates into two parts, a semisolid portion 

 termed myosin ( 53), and a fluid serum, which at ordinary temperature 

 quickly acquires an acid reaction. In the latter, as obtained from various 

 animals by different chemists, there have been discovered: 1. Various albu- 

 minous compounds ; small quantities of pepsin (Briicke) ; and a substance 



1 Virchow's Archiv, 1865, pp. 194 and 606. 



2 Zeits. f. rat. Med., Bel. xxxiii and xxxiv. 



See Tergast, Seluiltze's Archiv f. Microscop. Anatomic, Bd. ix, p. 36. 



