828 OF THE STRUCTURE AND FUNCTIONS OF MUSCULAR TISSUE. 



diately very stiff. Indeed it may be said that all circumstances which tend 

 to exhaust or depress the irritability of the muscles, such as death by slow 

 and wasting disease, violent muscular exertion immediately before death, or 

 powerful electrical shocks passed through the motor nerves, induce the early 

 appearance and speedy departure of this state putrefaction subsequently ap- 

 pearing and progressing rapidly. On the other hand, when the general 

 energy has been retained up to a short period before death, as in persons who 

 die from an accidental cause, or in animals the irritability of whose muscles 

 has been augmented by cold, cadaveric rigidity sets in late and lasts long, 

 and putrefaction also appears late and progresses slowly. Muscles deprived 

 of blood by the ligature of their arteries, or brought, into contact with dis- 

 tilled water, ammonia, dilute acids, alkaline salts, metallic salts, alcohol, or 

 chloroform (all of which produce coagulation of the myosin, whilst some of 

 them act on the other albuminous constituents of muscle), passjnto a state 

 closely analogous to, if not identical with Rigor mortis ; and within certain 

 limits their powers can be restored by the readmission of a current of duly 

 oxygenated or arterial blood. The contractile force exerted in Rigor mortis, 

 according to Hermann and Walker, 1 is generally less than, though some- 

 times fully equal to, or even greater than that which the muscle can exert 

 on strong electrical excitation. The condition of the muscles in post-mortem 

 rigidity is in many respects different from that of the contraction which 

 occurs during life. In the former the shortening is persistent and uniform, 

 the elasticity^ the tissue is increased; 2 and when it is induced by Heat, a 

 distinct diminution in the bulk of the muscle occurs; it feels firm and hard, 

 and there are no signs of electrical disturbance. In the latter, on the con- 

 trary, the contraction is intermittent, and there is, as we have seen, a dimi- 

 nution in the amount of the elasticity and of firmness, and evidence of a 

 change in the state of electrical tension (negative variation). In Rigor 

 mortis the muscles generally have an acid reaction; but this is not always 

 the case, and the two conditions are therefore independent of each other. 3 

 According to Ranke 4 and Hermann, living muscle absorbs far more oxygen 

 than dead ; as is shown in the following table : 



Excess of oxygen absorbed by living 

 Temperature. over dead muscle. 



2 C . 24.73 vol. per cent. 



7 _ 9 C., .... 14.72 " " 

 15 _ 20 C. (Hermann's Experiment), 3.61 " " 

 45 55 C., 2.01 " 



The absorption here indicated is clearly of a physiological nature, since it 

 steadily diminishes with increasing elevation of temperature, which hastens 

 the death of the muscle, and would prove favorable to any purely chemical 

 changes. 



678. It was formerly customary to divide the Muscles into two groups, 

 termed the "voluntary," and "involuntary," corresponding to the "striated" 

 and "non-striated" tissue respectively, but there are various circumstances 

 which show that this system of class! ficatiou cannot be consistently main- 

 tained. It is quite true that all the Muscles of Organic Life may be truly 

 styled "involuntary ;" for although they are capable of being influenced by 

 emotional and ideational states of mind, yet the Will cannot exert any 



1 Pfliiger's Archiv, Bd. iv, 1871, p. 182. 



2 There seems to be some difference of opinion on this point, Hermann and Walker 

 (Pfliiger's Archiv, 1871, vol. iv, p. 182) maintaining that muscles in rigor mortis pos- 

 sess a greater extensibility than contracted muscles. 



3 Wundt, Physiologic des Menschi-n, 1873, p 470. 

 * Die Lebensbedingungen der Nerven, 1868, p. 33. 



