360 THE MUSCLE-TISSUE. 



in water and dilute alcohol, but is insoluble in absolute alcohol and 

 ether. The substance does not reduce the metallic oxides in alka- 

 line solution, and is optically inactive. It is not fermentable with 

 common yeast, but is decomposed by the Bacterium lactis with the 

 formation of lactic acid, and subsequently yields butyric acid. 



Tests. Scherer's Test. If a few crystals of inosit are evaporated 

 on platinum foil with a little nitric acid, and the residue is treated 

 with ammonia and a drop of dilute solution of calcium chloride, a 

 rose-red spot remains on further evaporation. The reaction is due 

 to the formation of rhodizonic acid. 



Gallois' Test. On evaporating a small amount of a solution of 

 inosit and adding a few drops of a dilute solution of mercuric 

 nitrate before the residue has become dry, a yellow spot develops 

 on the further application of heat, which ultimately turns red. On 

 cooling, the red color disappears, but reappears on heating. 



Isolation. To demonstrate the presence of inosit in muscle- 

 tissue, this is finely hashed, and extracted with hot water, when the 

 albumins are removed by boiling. The filtrate is precipitated with 

 barium hydrate, so as to remove the phosphates that are present. 

 After filtering the liquid is then concentrated, until most of the 

 kreatin has separated out. This is removed by filtration ; the fil- 

 trate is boiled with four times its volume of alcohol ; the solution 

 is allowed to cool, freed from the mineral constituents that have 

 separated out, and shaken with ether. The inosit then separates 

 out in the form of fine platelets, which can be further purified by 

 dissolution in alcohol and reprecipitation with ether. 



The scyllite which is found in cartilaginous fish, where inosit 

 is absent, is closely related to the latter, and, like this, gives the 

 reaction of Gallois. 



THE NITROGENOUS EXTRACTIVES. 



The nitrogenous extractives of muscle-tissue comprise the com- 

 mon derivatives of the nuclear nucleins, viz., xanthin, hypoxanthin, 

 gtianin, and carnin ; further, traces of taurin, glycocoll, urea, and 

 uric acid ; and more abundantly kreatin and kreatinin. 



Kreatin and Kreatinin. Kreatin is a constant constituent of 

 the muscle-tissue of the vertebrate animals, while in the invertebrates 

 it has not as yet been found. Its amount is often quite considera- 

 ble, and it has been calculated that in adult man as much as !)() 

 grammes could be extracted from the muscles of the entire body. 

 Its anhydride, kreatinin, on the other hand, is usually found only 

 in traces, but may occur in larger amounts, and notably in certain 

 fishes. 



Of the origin of kreatin little is known, and it is noteworthy 

 that the substance has thus far not been obtained from the animal 

 li lies directly by artificial means. It has been found in the brain, 

 in the thyroid gland, in the blood, in transudates, in the amniotic 



