368 THE MUSCLE-TISSUE. 



which is taken from Gautier. The figures have reference to 100 

 volumes of blood, calculated at C. and 1000 Hgmm. pressure: 



Carbon 

 Oxygen, dioxide. 



Arterial blood from muscle-tissue 15.25 26.71 



Venous blood from muscle-tissue while at rest . . 6.70 33.20 

 Venous blood from muscle-tissue while at work . . 2.97 36.38 



In addition to carbonic acid, small amounts of nitrogen can fur- 

 ther be obtained from muscle-tissue, which are manifestly absorbed 

 from the blood and apparently exist in a state of solution. As in 

 other tissues and fluids of the body where nitrogen is also found, its 

 presence is probably of no significance. The quantity that can be 

 obtained by the vacuum pump is essentially the same as that which 

 is found in the lymph and in the blood. 



FAT. 



The amount of fat which is found in muscle-tissue varies not only 

 with different animals but also in one and the same individual at 

 different periods of life. Some of the analytical results which have 

 been obtained are shown below : 



Pro mille. 



Lean beef 6.1-7.6 



Rabbit 10.7 



Partridge 14.3 



Pig 40.0-90.0 



Salmon 100.0 



Mackerel 164.0 



Eel 329.0 



The fat is deposited not only in the interfibrillary connective 

 tissue, but also in the sarcoplasm proper, and is apparently more 

 abundant in the red meat, which contains more sarcoplasm than in 

 white meat. 



Like glycogen, it here represents a reserve source of muscular 

 energy, but is apparently utilized more especially when a sufficient 

 supply of the former or of grape-sugar, as such, is not available. 



While it is ordinarily derived from the ingested fats or from carbo- 

 hydrates, there can be no doubt that under certain pathological condi- 

 tions, which are associated with an increased destruction of tissue 

 albumins, it can also originate from these. This question, however, 

 we shall not consider in detail at this place, but shall revert to it in 

 a future section. 



In addition to fats, muscle-tissue also contains a small amount of 

 cholesterin, fats, and fatty acids, and at times considerable quanti- 

 ties of lecithins (0.69 per cent.). 



The chemical composition of involuntary muscle-tissue is essen- 

 tially the same as that of the striped variety. 



