igii] William H. Welker 71 



are less than those obtained from equal amounts of the same ma- 

 terial by incineration. It is probable that in this process there is a 

 certain degree of production of free inorganic molecules (ions), 

 especially as a result of hydrolytic dissociations of complex intra- 

 cellular Compounds of organic-inorganic types. These dialysis ex- 

 periments have been imdertaken in due appreciation of the present 

 paucity of knowledge regarding the nature of the intracellular in- 

 organic substances and are being continued in the hope of increas- 

 ing our information along these fundamental lines. 



Our general knowledge of the conditions and characters of in- 

 tracellular inorganic substances is stated briefly in the following 

 summary. 



All cells require inorganic salts for their growth and mainte- 

 nance, and for the exercise of their vital activities. Cells speedily 

 die when all inorganic salts are continuously denied them, how- 

 ever favorable all the other conditions for cellular existence 

 may be. Cellular activities are rendered pathological, when the 

 equilibrium among the intracellular salin substances is materially 

 disturbed by an abnormal increase or decrease in the proportion of 

 any one salin substance or ion. 



All cells yield inorganic substances by incineration, by simple ex- 

 traction and by dialysis. Of the inorganic mass obtained by direct 

 incineration, or by burning extracts or diffusates, much is pyrog- 

 enous, as has already been stated, and, there fore, cannot truly 

 represent intracellular inorganic matter. Of the inorganic masses 

 obtained by extraction and dialysis, some is apparently produced 

 from complex intracellular Compounds by hydrolytic dissociation. 

 Some of the intracellular inorganic matter seems to occur in 

 the form of ordinary salts. A small proportion of this simple 

 salin matter, such as calcium phosphate, may be suspended in the 

 intracellular mass, but most of the true salin material appears to 

 be dissolved in the intracellular water, where the salts evidently 

 exist in molecular forms and also in ionized states. This piain 

 inorganic matter is characterized biologically by its mobility, its 

 osmotic power, and its readiness to enter into new chemical reac- 

 tions of great functional import under the influence of changing 

 extracellular as well as intracellular conditions. 



" Organic combinations " of inorganic materials occur in cells in 



