552 MUSCULAR RIGIDITY. 



a more active decomposition of albuminates. The excretion of sulphur is increased 

 by muscular exertion, and indeed the non-oxidized sulphur is at first excreted 

 more rapidly than the oxidized. The excretion of phosphoric acid also is in- 

 creased. 



7. In the muscles of animals the amount of glycogen (0.43 per cent.) 

 has been observed to diminish as a result of activity, and even to dis- 

 appear completely in consequence of strychnin-convulsions. The same 

 observation has been made with respect to the glycogen of the liver. 

 Luchsinger maintains that muscles can still contract when completely 

 free from glycogen; so that the latter cannot be the source of muscular 

 energy. Also, the sugar of the blood undergoes a decrease in the muscles 

 as a result of activity. 



There is a difference of opinion as to whether the muscle-glycogen is carried 

 by the circulation from the liver into the muscles, or whether it is produced in 

 the muscular tissue itself as the result of an as yet unknown decomposition of 

 the albuminates. Ktilz observed an increase in the amount of glycogen in the 

 muscles of frogs that had been deprived of their livers after subcutaneous injections 

 of sugar. Likewise, the muscles retained their glycogen for a much longer time 

 than the liver during the state of hunger. These facts indicate the formation of 

 glycogen in the muscular substance itself. In any event, the normal circulation 

 is a requisite for the production of glycogen in muscle, for this diminishes after liga- 

 ture of all of the vessels. Surviving muscle converts glycogen into sugar. 



Some investigators, however, assume also that not only proteid 

 but, in part, also fat and carbohydrate may be the source of muscular 

 energy in the body. 



MUSCULAR RIGIDITY (CADAVERIC RIGIDITY, RIGOR MORTIS). 



Excised muscles, striated as well as unstriated, and also the muscles 

 of the intact body some time after death, pass into a state of rigidity, 

 described more fully later on, that is designated muscular rigor. If 

 the muscles of the dead body become involved, the entire cadaver be- 

 comes completely stiff (cadaveric rigidity). The cause of this phenome- 

 non resides in a spontaneous coagulation of the myosin within the muscle- 

 fibers, with the development of a small amount of acid. During this 

 process of coagulation, heat is liberated owing to the transition of the 

 fluid myosin into the solid condition, and, also, owing to the thickening 

 of the tissue that takes place at the same time. 



Myosin, dissolved in a 5 per cent, solution of magnesium sulphate diluted with 

 water, separates after a time in the form of solid flakes, with the development 

 of an acid reaction. Warming hastens this process. 



_ The rigid muscle exhibits the following properties: It is shortened, 

 thickened, and somewhat denser; stiff, firm and solid; turbid and opaque, 

 in consequence of the coagulation of the myosin; incompletely elastic, 

 less extensible, and less readily torn. It is completely unresponsive to 

 stimuli, and its electrical potential has disappeared. The amount of 

 glycogen present is diminished. Striated muscle has an acid reaction, 

 on account of increased formation of the two varieties of lactic acid (un- 

 striated has not), and it develops free carbon dioxid. If incisions be 

 made into rigid muscles, a fluid exudes spontaneously, the muscle- 

 serum. 



The view was formerly held that during rigidity, partial or complete trans- 

 formation of the glycogen occurred, first into sugar and then into lactic acid. 

 This view, however, has been contested by Bohm, who asserted that during 



