124 STUDIES IN ADVANCED PHYSIOLOGY. 



and a peculiar kind of muscle sugar called inosit: further, 

 traces of haemoglobin, whence their color, bits of organic 

 compounds such as kreatin, which will be discussed further 

 in the chapter on excretion, and finally the important sub- 

 stance, muscle albumen. Just in what form this muscle 

 albumen is in a living muscle it is impossible to determine, 

 for in order to investigate the albumen it is, of course, 

 always necessary to destroy the vitality of the muscle. If, 

 however, perfectly fresh muscle be taken and then cooled 

 almost to the freezing point, then cut into small pieces and 

 the liquid pressed out through a cloth, there may be filtered 

 out in this way a slightly yellowish-colored fluid called 

 muscle plasma. This muscle plasma at ordinary tempera- 

 tures coagulates much like the blood, and soon presses out 

 of itself a serum much like a blood clot would, which serum 

 is called muscle serum. The substance, which forms the 

 solid portion of the clot, is familiar to all students of physi- 

 ology under the name of myosin. This myosin is insoluble 

 in water, but soluble in common salt solutions, and also 

 soluble in dilute acids. When dissolved in dilute acids it 

 is changed into syntonin, which is, therefore, in reality 

 merely an acid solution of myosin. The blood plasma 

 which has been pressed out of the clot contains several 

 albumens, the principal one being ordinary serum albumen. 

 The nutritive value of muscles is derived, to a large 

 extent, from these albumens. As most of them are, how- 

 ever, insoluble in water and easily coagulated by heat, but 

 little of the albumens is removed by boiling. The mineral 

 salts and the flavors are of course easily extracted by boil- 

 ing water, and so may give to the liquid quite a strong 

 taste, which may mislead the person into the belief that the 

 strong taste is an evidence of its nutritive value. It is well 

 to bear this in mind, as attempts are frequently made to 

 nourish people on variously prepared soups and broths, in 

 the belief that the boiling of the meat has extracted from 

 it its nutritive ingredients. A little of the albumen may pos- 

 sibly thus be extracted, but the nutritive property of it is 



