GLANDULAR ORGANS. 5 



present. 1 The mucus of urine has also been stated to be nucleo-proteid in 

 nature. 2 K. A. H. Morner 3 investigated healthy human urine ; each experiment 

 necessitated the use of 80-90 litres. He found proteid or proteid-like materials 

 partly in suspension in the ordinary mucous cloud or nubecula, and partly in 

 solution. From the nubecula he separated a specific member of the mucin 

 group, which he calls urine mucoid. This probably originates from the mucous 

 membrane of the urinary passages. It contains C 49 '4, N 12 '74, and 

 S 2*3 per cent. ; and in its general properties agrees with ovo-mucoid pretty 

 closely (see p. 63). The soluble proteid in urine, which is present in the 

 merest traces, is chiefly serum albumin, but some is precipitable by acetic 

 acid, and this part consists of a nucleo-proteid; precipitated with it was 

 found a small quantity of chondroitin sulphuric acid (see " Cartilage " ). 



The mucin of the respiratory passages has been investigated by F. Miiller. 4 

 He finds it is true mucin, not nucleo-proteid. It yields from 25 to 32 per cent, 

 of reducing substance. This is a nitrogenous derivative of a hexose, and is 

 probably glucosamine. 



Keratin and the skeletins are epithelial products which have already been 

 described (p. 72). The enamel of teeth, although epithelial in origin, will 

 be taken with the skeletal tissues. The epithelium of secreting glands will 

 be studied with those glands and their secretions. 



GLANDULAK ORGANS. 



The liver. The fresh liver is alkaline in reaction, but after death 

 soon becomes acid from the development of sarcolactic acid. 



The number of organic substances in the liver is very numerous. 

 There are proteids and nuclein from the hepatic cells; there are 

 substances like glycogen, sugar, and fat, stored up within the cells, or 

 produced from stored-up substances. Gelatin and mucin are obtainable 

 from the connective tissue framework. There are also extractives like 

 xanthine, hypoxanthine, and uric acid; lastly, a small proportion of 

 inorganic constituents. 



The proportion of water is about 75 per cent. v. Bibra 5 gives the 

 following numbers : 



Water . . 76 '17 per cent. 

 Insoluble tissues 9 - 44 

 Proteids . 2 '40 



Gelatin . . 3'37 per cent. 

 Extractives . 2 -40 

 Fats 2-50 



Proteids of the liver cells. These were first investigated by P. Plosz. 6 

 He found that, accompanying the onset of acidity after death, the 

 liver became harder and less transparent; he therefore compared the 

 condition to the rigor mortis of muscle, and sought for myosin by the 

 methods Kiihne had introduced for separating muscle plasma. He did 

 not, however, find any myosin. He extracted the proteids by means of 

 saline solutions of various strengths, and found 



(1) A proteid coagulating at 45 C., wholly soluble in gastric digestion ; 

 (2) a nucleo-proteid, coagulating at 70 C., yielding an insoluble residue of 



1 Hanmiarsten, Km. Ges. der Wiss., Upsala, 1893 (Separat-abzug) ; Baginsky anrl Somer- 

 feld, Verhandl. d. pliysiol. Gesellsch., Berlin, 1894-5, Nos 13, 14, 15 in Arch. f. PhysioL, 

 Leipzig, 1895, S. 362. 



a L6nnherg, Upsala Lakarcf. Fork., vol. xxv. ; K. Morner, Hygiea, Stockholm, 1892, 

 vol. lii; Obennayer, CentralbL f. Uin. Med., Bonn, Bd. xii. 



* Skandin. Arch. f. PhysioL, Leipzig, 1895, S. 332. 



4 Sitzungsb. d. Gesellsch. z. Beford. d. ges. Naturw. zu Marburg, 1896, No. 6. 



5 v. Bibra, "Chemische Fragments ueber die Leber," 1849. 



6 Arch.f. d. ges. PhysioL, Bonn, Bd. vii. S. 371. 



