LACK OF MINERAL SUBSTANCES. 899 



If water is withdrawn for a certain time, as LANDAUER and espe- 

 cially STRAUB have shown, it has an accelerating influence upon the 

 decomposition of protein. This increased destruction has, according to 

 LANDAUER, the purpose of replacing a part of the water removed, by the 

 production of water by means of the increased metabolism. The depriva- 

 tion of water for a short time may, according to SriEGLER, 1 especially in 

 man, cause a diminution in the protein metabolism by means of a reduced 

 protein absorption. 



Lack of Mineral Substances in the Food. In the previous chapters 

 attention has repeatedly been called to the importance of the mineral 

 bodies and also to the occurrence of certain mineral substances in certain 

 amounts in the various organs. The mineral content of the tissues and 

 fluids is not very great as a rule. With the exception of the skeleton, 

 which contains as average about 220 p. m. mineral bodies (VOLKMANN 2 ), 

 the animal fluids or tissues are poor in inorganic constituents, and the 

 quantity of these amounts as a rule, only to about 10 p. m. Of the 

 total quantity of mineral substances in the organism, the greatest part 

 occurs in the skeleton, 830 p. m., and the next greatest in the muscles, 

 about 100 p. m. (VOLKMANN). 



The mineral bodies seem to be partly dissolved in the fluids and partly 

 combined with organic substances, but nothing definite can be given as 

 to the kind of combination, or whether they occur in stoichiometric 

 proportions, or whether they are simply adsorption combinations. In 

 accordance with this the organism persistently retains, with food poor 

 in salts, a part of the mineral substances, also such as are soluble, as the 

 chlorides. On the burning of the organic substances the mineral bodies 

 combined therewith are set free and may be eliminated. It is also 

 admitted that they in part combine with the new products of the com- 

 bustion, and in part with organic nutritive bodies poor in salts or nearly 

 salt-free, which are absorbed from the intestinal canal and are thus retained 

 ( VOIT, FORSTER 3 ) . 



If this statement is correct, it is possible that a constant supply of 

 mineral substances with the food is not absolutely necessary, and that the 

 amount of inorganic bodies which must be administered is insignificant. 

 The question whether this is so or not has not, especially in man, been 

 sufficiently investigated; but generally we consider the need of mineral 



1 Landauer, Maly's Jahresber., 24; Nothwang, Arch. f. Hyg., 1892; Straub, Zeitschr. 

 f. Biol., 37 and 38; Spiegler, ibid., 41. 



2 See Hermann's Handbuch., 6, pt. 1, 353. 



3 Forster, Zeitschr. f . Biologic, 9. See also Voit, in Hermann's Handbuch, 6, 

 Part 1, 354. In 'regard to the occurrence and the behavior of the various mineral 

 constituents of the animal body see the work of Albu and Neuberg, Physiologic und 

 Pathologic des Mineralstoffwechsel, Berlin, 1906. 



