24 CHEMICAL CONSTITUENTS OE BODY AND FOOD. 



It forms, like glycerine, compounds often called esters, with fatty acids ; 

 and these compounds, which are found in the fatty secretions of the skin, 

 especially in the fat of sheep's wool (lanoline), are very resistant to bacterial 

 action ; as a protection to the skin lanoline is therefore admirable. 



In lanoline there are two cholesterins at least; one is levorotatory, the 

 other (isocholesterin) is dextrorotatory. Isocholesterin was first described 

 by Schultze, 1 and does not give Salkowski's reaction. 



Cholesterins of various kinds are present in vegetable tissues. 2 



The cholesterin of the blood is in combination with oleic and palmitic 

 acids. 3 



In man the cholesterin of the bile passes away in the fseces as koprosterin 

 (C. 2T H 4S 0) ; in the horse as hippokoprosterin (C 27 H 54 or C 27 H 56 0) ; in the dog 

 it is unchanged. 4 



THE PROTEIDS. 5 



The proteids are the most important substances present in animal 

 and vegetable organisms ; none of the phenomena of life occur without 

 their presence ; they are constant decomposition products of, and therefore 

 probable constituents of, protoplasm. 



" They are highly complex and, for the most part, uncrystallisable 

 compounds of carbon, hydrogen, oxygen, nitrogen, and sulphur, 6 occurring 

 in a solid, viscous condition, or in solution in nearly all the solids and 

 liquids of the organism. The different members of the group present 

 differences in physical, and to a certain extent even in chemical 

 properties. They all possess, however, certain common chemical reactions, 

 and are united by a close genetic relationship " (Gaingee). 7 



The following table from Gorup-Besanez 8 exhibits the percentage of 

 proteids contained in the liquids and solids of the body : 



Cerebro-spinal fluid . 0'09 



Aqueous humour . . 0*14 



Liquor amnii . . 0*70 



Intestinal juice . . 0'95 



Pericardial fluid . . 2 -36 



Lymph . . . 2*46 



Pancreatic juice . . 3 - 33 



Synovia . . . 3 '91 



Chyle . 4-09 



Blood . . 8-56 



Spinal cord . . 7*49 



Brain . . . S'G3 



Liver . . . 11 -64 



Thy mus . . 12 '29 



Muscle . . 16-18 

 Tunica media of arteries 27*33 



Milk .... 3-94 Crystalline lens . 3S'30 



1 J3er. d. deutsch. chem. Gesellsch., Berlin, Bd. vi. ; Journ. f. prakt. Chcm., Leipzig, 

 N.F., Bd. xxv. S. 458; Ztschr. f, physiol. Chem., Strassburg, Bd. xiv. S. 522. On 

 isocholesterin in remix caseosa see Rappel, ibid., Bd. xxi. S. 122. 



2 Beneke, Jahresb. ii. d. Leistung d. ges. Med., Berlin, 1862 ; Hesse, Ami. d. 



Chem., Leipzig, Bd. cxcii. S. 177; Bd. ccx., S. 283; Reinke and Rodewald, ibid., Bd. 

 ccvii. S. 232; Schulzc and Barbieri, Journ. f. prakt. Chem., Leipzig, N.F., Bd. xxv. S. 

 159, 458; Heckel and Schlagdenhauffen, Compt. rend. Acad. d. sc., Paris, 1886, tome cii. 

 p. 1317 ; Arnaud, ibid., p. 1319. See also Jacobson's paper on " Vegetable Oils," Ztschr. 



f. physiol. Chem., Strassburg, Bd. xiii. S. 32. 



3 K. Hiirthle, Ztschr. f. physiol. Chem., Strassburg, 1896, Bd. xxi. S. 331. 



4 St. Bondzynski and V. Hunmicki, Ztschr. f. physiol. Chcm., Strassburg, 1896, Bd. 

 xxii. S. 396. 



5 In the preparation of this section I have derived special assistance from the articles 

 "Eiweisskorper," in Beilstein's " Handbuch der org. Chemic," and in Ladenburg's 

 " Handworterbueh d. Chemie," 1885, Bd. iii. S. 534 (article by E. Drechsel) ; and from 

 an article by T. G. Brodie in Science Progress, London, 1895, vol. iv. p. 62. 



6 In some cases phosphorus also is present. 



7 "Physiological Chemistry," London, vol. i. p. 4. 



8 "LehrbucV'S. 128. 



