466 METABOLISM IN MUSCLE. 



investigations on this subject Fick and "Wisliceuus (1866) ascended the Faulhorn, and for 

 seventeen hours before and for six hours after the ascent no proteid food was taken the diet 

 consisting of cakes made of fat, sugar, and starch. The urine was collected in three periods, as 

 follows : 



Fick. Wislicenus. 



1. Urea of 11 hours before the ascent, . I 238*55 grs. 



2. ,, 8 ,, during 109*44 ,, . 



3. 6 ,, after 80'33 , 



221 -05 grs. 



': j 183,5 



A hearty meal was taken after this period, and the urine of the next eleven hours after the 

 period of rest contained 159 "15 grains of urea (Fick), and 17671 ( Wisliceuus). All the experi- 

 ments go to show that the amount of urea excreted in the urine is far more dependent upon the 

 nitrogen ingested, i.e., the nature of the food, than upon the decomposition of the muscular 

 substance. A vegetable diet diminishes, while an animal diet greatly increases, the amount of 

 urea in the urine. North's researches confirm those of Parkes, but he finds that the disturbance 

 produced by severe muscular labour is considerable. The elimination of phosphates is not 

 affected, while the sulphates in the urine are increased.] 



During the activity of a muscle, all the groups of the chemical substances 

 present in muscle undergo more rapid transformations (J. Ranke). It is still a 

 matter of doubt, therefore, whether we may assume that the kinetic energy of a 

 muscle is chiefly due to the transformation of the chemical energy of the 

 carbohydrates which are decomposed or used up in the process of contraction. As 

 yet we do not know whether the glycogen is supplied by the blood-stream to the 

 muscles, perhaps from the liver, or whether it is formed within the muscles 

 themselves from some unknown derivative of the proteids. The normal circulation 

 is certainly one of the conditions for the formation of glycogen in muscle, as 

 glycogen diminishes after ligature of the blood-vessels (Chandelon). A muscle in 

 which the blood circulates freely is capable of doing more work than one devoid of 

 blood, and even in the intact body, more blood is always supplied to the contracted 

 muscles. 



[Source of Muscular Energy. The experiment of Fick and Wislicenus 

 definitely proved that the proteids are not the exclusive, or by any means the 

 chief source of muscular energy. As it is conclusively proved, that during 

 muscular work, there is a great increase in the amount of O absorbed, and C0 2 

 given off, it is evident that the non-nitrogenous substances of the food must be 

 the chief sources of this energy. We turn naturally to the carbohydrates, and as 

 the latter are chiefly stored up in the form of glycogen in the muscles, it is 

 assumed that glycogen is the chief source of the energy. Glycogen in muscle 

 diminishes during muscular work, and is stored up during rest (Bernard). Kiilz 

 also found that in dogs the glycogen disappears from the liver during work, and 

 Voit found that the muscle-glycogen disappears before that in the liver. It 

 appears, therefore, that the carbohydrates are a source of muscular energy. But 

 they, again, are not the only source. It is highly probable that glycogen can be 

 formed from proteids, and it is allowable, therefore, to assume that 2>roteids may 

 also serve as a source of muscular energy. If this be not so, it is difficult to 

 understand how carnivora can be fed and maintained in good health for long 

 periods on lean flesh. The fats are probably also another source. Hence, it would 

 appear that all three of the chief groups of food-stuffs carbohydrates, proteids, 

 and fats may serve as the source of muscular energy ; but that, so long as non- 

 nitrogenous elements are supplied in the food in sufficient quantity, or are stored 

 up in the body, the muscles do their work chiefly on these. After they are used up, 

 the proteids are, as it were, called up.] 



295. RIGOR MORTIS. Cause. Excised striped, or smooth muscles, and 

 also the muscles of an intact body, at a certain time after death, pass into a 

 condition of rigidity cadaveric rigidity or rigor mortis. When all the muscles 



