22 INTRODUCTION. 



about two-thirds water. If we also recall that water is of the very 

 greatest importance for the normal physical condition of the tissues, 

 that the solution of numerous bodies and the dissociation of chemical 

 compounds, that all flow of juices, all exchange of material, all supply 

 of food, all growth or destruction and all removal of destructive prod- 

 ucts, are connected with the presence of water, and that besides this the 

 water by its evaporation is an important regulator of temperature, if 

 is evident that water must be a necessity of life. 



The mineral substances found habitually in the cells of higher plants 

 and of animate are potassium, sodium, calcium, magnesium, iron, phos- 

 phoric acid, sulphuric acid, chlorine, and perhaps also iodine (JUSTUS). 1 

 Besides, in certain cells or organs we also find manganese, lithium, barium, 

 silicium, fluorine, bromine, and arsenic. 



We are chiefly indebted to LIEBIG for showing that the mineral 

 bodies are as important for the normal constitution of the organs and 

 tissues, as well as for the normal performance of the processes of life, 

 as the organic constituents of the body. The importance of the mineral 

 constituents is evident from the fact that we know no animal tissue 

 and no animal fluid which is free from mineral bodies, and also from 

 the fact that certain tissues or tissue elements contain chiefly certain 

 mineral bodies and not others. In regard to the alkali compounds this 

 division is, in general, as follows: The sodium compounds occur chiefly 

 in the fluids, while the potassium compounds occur especially in the 

 form-elements. Corresponding to this, the cells contain chiefly potas- 

 sium as phosphate, while they are less rich in sodium and chlorine com- 

 pounds. Still we have some exceptions to this rule, and it must be 

 remarked that BEEBE 2 has found considerably more sodium than 

 potassium in malignant tumors. 



The division of the mineral bodies in the various parts of a cell cr a 

 tissue is very difficult to determine, but in certain cases by means of 

 micro-chemical reactions this can be determined in a way. For example, 

 MACALLUM 3 has been able to show such a division in the case of potas- 

 sium. According to him the potassium is absent in the cell nuclei and 

 in the head of the spermatozoa as well as in the nerve cells and the axis- 

 cylinders, while it occurs on the contrary in the medullary sheath and 

 especially in the region of the nodes of RANVIER. 



1 Justus, Virchow's Arch., 170, 176 and 190. In regard to arsenic see the works of 

 Gautier, Compt. rend., 129, 130, 131, 139; Bertrand, ibid., 134; Segale, Zeitschr. f. 

 physiol. Ohem., 42; Kunkel, ibid., 44. In regard to the barium see Schulze and 

 Thierfelder, Sitzimgsber. d. Gesellsch. naturforsch. Freunde, 1905, No. 1, and in 

 regard to lithium see Hermann, Pfluger's Arch., 109; and in regard to manganese 

 see Bradley, Journ. of Biol. Chem., 3. 



2 Amer. Journ. of Physiol., 11 and 12. 



3 Journ. of Physiol., 32. 



