NDTRITION OF MUSCLES 277 



of digesting proteid, and an amylotio enzyme which changes glycogen 

 to sugar, a glycolytic enzyme which destroys sugars, a fat enzyme 

 or lipase which breaks up fats, and finally an enzyme which causes 

 the clotting of myogen and myosin after death. 



Inorganic muscle constituents. — Muscle contains many salts 

 which aid in securing an interchange of nutrition by osmosis and 

 dialysis with the lymph and blood through the sarcolemma, and 

 they also give to the muscle its irritability and sensitiveness to 

 nerve stimuli. 



Water forms 75% of the living muscle. 



Pigments and other components. — The red color of muscle is 

 due partly to the blood it contains, and partly to a pigment, sim- 

 ilar to haemoglobin, called myohajmatin, which probably aids the 

 muscle cell to absorb oxygen. 



Muscle also contains several organic acids and nitrogenous 

 wastes. 



Nutrition of Muscles. — Muscles are penetrated every- 

 where by blood vessels. From the larger blood vessels 

 smaller branches are given off, and these end at the 

 capillaries which surround the finest bundles of the muscle 

 mass. From the lymph which comes from these blood 

 vessels, the muscle fibers select their food and give off 

 their wastes to it. (See p. 175.) From the blood they 

 also receive oxygen and give up the carbon dioxide to it. 



