CHEMICAL COMPOSITION OF THE BODY. 



but often also in the form of spheroid or hemispheroidal masses, or of an 

 aggregate of one large spheroid with several smaller ones adherent to it. 

 The spheroids either present a concentric lamination or are destitute of this 

 and resemble fat-cells. It is destitute of taste and smell, is soluble in 27 

 parts of cold water, but is nearly insoluble in cold ether or alcohol. Its 

 aqueous solution is neutral. It unites both with acids and with bases. It 

 is largely present in the pancreas and pancreatic juice, and is also found in 

 the salivary glands and saliva, in the spleen, kidneys, and suprarenal bodies ; 

 in the thymus, thyroid, and lymphatic glands, in the fluids of the lungs, and 

 in pus, and occasionally in the urine, especially in cases of acute atrophy of 

 the liver. It is either absent or only traces of it can be found in the healthy 

 liver, brain, and muscles. It is in all probability a product of the retro- 

 gressive metamorphosis of gland tissue. It has been artificially obtained 

 by Kiihne from the action of the pancreatic ferment on albumen. Frerichs 

 and Stiideler have shown it to be probable that it undergoes decomposition 

 in the alimentary canal, into ammonia, and the volatile fatty acids. 



TYROSIN, C 9 H U NO 3 . This substance is likewise an amido-acid and forms 

 delicate white silky needles, which have no taste or smell, are soluble with 



difficulty in cold water, and are insoluble in al- 

 cohol and ether. When boiled with Millon's 

 reagent, the solution first assumes a beautiful red 

 color, and then quickly throws down a dark- 

 brown red precipitate. Tyrosin is said to be 

 found iii the spleen and pancreas, and in acute 

 atrophy of the liver in that gland, in the brain, 

 and in the urine; but it is probable, from Rad- 

 ziejewsky's researches, 1 that it never occurs in 

 any organ in a normal condition, with the single 

 exception of the contents of the small intestines, 

 where it results from the decomposition of albu- 

 minous compounds under the influence of the 

 a pancreatic juice. Heated with concentrated sul- 

 phuric acid it forms Tyrosin-sulphuric acid to- 

 getlier with other acids. The former gives a 

 beautiful violet color, with iron and its salts 

 (Piria's test). Tyrosin, like Leucin, is to be regarded as a product of the 

 disintegration of the albuminous compounds. 



KREATIN, C^gN^ + H 2 O. This substance is a constant constituent 

 of muscular tissue, both of the striped and smooth variety, in the propor- 

 tion of from 2 to 4 parts in 1000; and is found in the blood, brain, urine, 

 and amniotic fluid. It crystallizes in oblique rhombic prisms, which are 

 soluble in hot water, but are deposited again on cooling. It dissolves with 

 difficulty in alcohol, and is insoluble in ether. It is prepared by exact pre- 

 cipitation of the phosphates in the juice of meat with acetate of lead; sepa- 

 ration of the lead by means of sulphuretted hydrogen and careful evapora- 

 tion. On boiling it with baryta water, it is converted into sarkosin a 

 substance closely related to the glycin of the bile and urea, which imme- 

 diately splits up into ammonia and carbonic acid. When heated with acids, 

 or even after long exposure to the action of hot water, it loses two atoms of 

 water and becomes converted into kreatinin. Under other circumstances, 

 instead of producing sarkosin and urea, it may decompose into oxalic acid 

 and a substance termed inethyl-uramin, which shinds in close connection 

 with guanin, xanthin, hypoxanthin, and uric acid; all of which relations 



Tyrosin. 



1 Virchow's Arcbiv, 18G6, May. 



