CHEMICAL COMPOSITION OP THE BODY. 99 



salivary and gastric fluids; in mucus, pus, and inflammatory cxudates; 

 whilst, it is remarkably deficient in the yolk of eggs, in the juice of muscles, 

 and in the secretion of some glands. Its uses are numerous. It exerts an 

 important influence on all the diffusion processes that take place in the body, 

 affecting in this way the absorption and interchange of material ; whilst by 

 conferring, in association with other salts, a certain density upon the blood 

 plasma, it plays an important part in the conservation of the morphological 

 elements of the blood in their natural condition. It also seems to be essen- 

 tial to the performance of many of the metamorphic and histogenetic opera- 

 tions to which the organic constituents of the food are subjected in the 

 animal economy. It was demonstrated by Boussingault, 1 that when, of two 

 sets of oxen, one was allowed the unrestricted use of salt, whilst the other 

 was as far as possible deprived of its use, a marked contrast was observable 

 in the course of a few weeks between them, and manifestly to the advantage 

 of the former. The desire for common salt on the part of animals and man 

 is extremely powerful, leading the former, especially if they be vegetable 

 feeders, to traverse great distances to reach saline deposits : whilst strong 

 evidence of the necessity for its use in man is afforded by the fact mentioned 

 by Bru'cke, that many military deserters who live a wild life in the moun- 

 tains of Salzburg, Upper Austria and Carinthia, risk their liberty and even 

 lives to obtain it in town or village. Sodium phosphate (Na.,HPO 4 and 

 Na 4 H. 2 PO 4 ) and carbonate, the latter of which is partly ingested with the 

 food, and partly results from the decomposition of the salts of malic, citric, 

 and tartaric acids, would seem to have as their chief purpose the mainte- 

 nance of the alkalinity of the blood, on which depends not merely the 

 solubility of its albumen, but the facility of its passage through the capil- 

 laries, and the readiness with which its combustive materials are oxidized, 

 whilst they also increase the absorptive power of the serum for gases, and 

 thus play an important part in the respirator) 7 process. The salts of potash 

 appear to be specially required for the nutrition of the muscles and nerves, 

 since they are largely present in the fluids and ashes of those tissues, but 

 they probably exert the same general influence as those of soda. The 

 quantity present in the blood cannot exceed certain limits, since the observa- 

 tions of Graudeau and others 2 have shown that the injection of potassium 

 salts, and especially of potassium chloride, are even in dilute solution highly 

 poisonous, paralyzing the heart and striated muscles. It is remarkable'that 

 when injected into the stomach the action of the chloride is different, in- 

 creasing the frequency and force of the heart's action, and the pressure of 

 the blood. 3 The presence of the earthy salts, on the other hand, would seem 

 to have reference almost exclusively to the composition of the tissues, into 

 which some of them enter very largely. Calcium phosphate, in particular, 

 must be regarded almost in the light of a histogenetic substance so constantly 

 is it present in newly forming tissues, whilst it is also in great demand as 

 the principal consolidating material of bone and tooth. Whether the cal- 

 cium carbonate, magnesium phosphate, the calcium fluoride, and the silica, of 

 the blood, are of any other use than to supply consolidating materials for the 

 tissues, there is at present no evidence whatever. Iron, like the alkaline 

 salts, is an essential constituent of the blood itself, forming a large percent- 

 age of the hpematoglobuliu of its red corpuscles, and it is supplied by the 

 blood to various tissues, especially the muscles and the hair, of which also it 

 may be considered an essential component. Estimating the quantity of 



1 Memoire de Ghemie Aiirk-ole, 1854, p. 271. 

 ! Traube, Bernard, Ranke, Pnduapaw, and Guttmann. 

 3 Kemmerich, Archiv f. Phys., Band ii, p. 49. 



