296 MANUAL OF HISTOLOGY. 



contents. Finally, we should analyse the fluid saturating muscles, with 

 its nutritive matters and products of decomposition resulting from the 

 energetic transformative processes going on in the tissue. 



Zoochemistry, however, of the present day is unable to meet these 

 requirements of physiology; and yet, muscle is one of those tissues 

 which has received most attention to this end. In the year 1847, 

 Liebig presented us with his elaborate treatise, and, more recently, Kuhne 

 has essentially furthered our acquaintance with the subject by his elegant 

 experiments on the muscles of frogs. 



From the already mentioned microchemical bearing, we gather that the 

 substance of the sarcous elements, of the longitudinal and of the transverse 

 cement, is to be recognised as three distinct materials with separate 

 reactions. We have still, then, the nucleus, insoluble in acetic acid, 

 dark transverse disk of Krause (also of resistent nature), and the sarco- 

 lemma, with its reactions so similar to elastic tissue (but greater solubility 

 in alkalies); so that, taken in all, there is very considerable complexity to 

 be coped with. 



The specific gravity of striated muscle is stated to lie between 1'055 

 (G. Krause) and 1'041 (W. Krause and Fischer), while the proportion of 

 water contained in it ranges from 78 to 72 per cent. (1). This water belongs 

 first of all to the tissue of the fibres, then to the other structural con- 

 stituents scattered among the latter, and finally, to the fluids with which 

 the whole mass is saturated, the amount of which, however, is not yet 

 known. This latter has been named the "muscle plasma," Like the 

 plasmatic fluid of the blood, it loses, on the death of the muscle and con- 

 sequent "spontaneous" coagulation as it is called, an albuminous substance, 

 and becomes " muscle-serum " (Kuhne). 



The juice of living muscle has a distinctly alkaline reaction (Du Bois- 

 Reymond) ; that of the dead tissue, or that affected by rigor mortis, is acid 

 (Liebig). 



From the solid constituents of muscular tissue, which amount to some- 

 where about 20 per cent., we have first a varying quantity of glutin'ous 

 matter to deduct, which belongs to the commingled connective-tissue. 

 About from 0-6 to 2 per cent, of glutin may be obtained from fresh muscle. 



The fresh tissue then contains, to the amount of 15-18 per cent., a series 

 of albuminous matters, partly soluble and partly insoluble, witli which 

 we are still but imperfectly acquainted. These are in the first place con- 

 stituents of the juices of the tissue, then again of the fleshy fibres of the 

 latter. The soluble members of the group are for the most part remark- 

 able for their coagulation at a low temperature (35-50 C.), a property 

 which is to be met with only in those of the contractile substances of the 

 system. 



Kuhne has obtained the spontaneously coagulating albuminous sub- 

 stance of the plasma from the muscles of frogs, and has named it myosin 

 ( 12). It is the congelation of the latter which communicates to the 

 fibre of muscle its cloudy appearance on rigor mortis setting in. The 

 coagulum of myosin is insoluble in water, but soluble in solutions of 

 common salt, which contain less than 10 per cent of CINa, likewise in 

 dilute acids and alkalies. 



Three other albuminous substances, besides, may be obtained, according 

 to the same observer, from muscle serum, namely, the so-called albuminate 

 of potash, a second material, coagulating at 45 C., and a third, which 

 requires 75 C., before the latter process takes place in it. 



