DISTURBANCE OF THE INORGANIC ENVIRONMENT 311 



The investigations thus initiated have been continued by a very large 

 number of subsequent observers whose labors have resulted in the 

 accumulation of our present extensive knowledge of the influence 

 of inorganic salts upon living matter. A large part of this information 

 belongs more appropriately to the subject of Pharmacology and we will 

 only review it here in so far as it throws an important light upon the 

 nature of the chemical and physicochemical factors which govern 

 the relationship of the cell to its normal environment. The detailed 

 actions of the inorganic substances which are rarely if ever constituents 

 of the normal inorganic environment of protoplasm we will therefore 

 not discuss beyond the enunciation of the brief generalisation that the 

 salts of the Heavy Metals such as silver, copper, lead and mercury, 

 act as corrosive poisons, leading to disintegration of the cells by coagu- 

 lation and flocculation of the protoplasmic proteins, which disrupts 

 the continuity of the gel-structure of the cell and causes it to break 

 up into particles which fall apart, so that the substance of the cell is 

 gradually eroded away. The compounds of Phosphorus, other than 

 the phosphates, and the compounds of Arsenic exert peculiar effects 

 on metabolism which are fully described in current works on pharma- 

 cology. 



The discovery that the inorganic salts which form the normal con- 

 stituents of the environment of cells may under certain circumstances 

 act as protoplasmic poisons, is attributable in the first place to Ringer 

 who, however, did not himself interpret his results in this manner. He 

 found that if the excised hearts or skeletal muscles of cold-blooded 

 animals be immersed in pure Sodium Chloride solution which is isotonic 

 with blood serum, they lose their irritability and the power of con- 

 traction much more rapidly than they do in blood serum, or in solutions 

 containing sodium, potassium and calcium chlorides in the proportions 

 in which they are present in blood-serum. This was at first interpreted 

 to mean that potassium and calcium were required by these tissues 

 for nutritive purposes, but later investigations have clearly shown that 

 while pure sodium chloride is definitely toxic for living tissues, its 

 toxic properties are antagonized or annulled by a correct admixture 

 of potassium and calcium salts. 



All Inorganic Salts in pure solutions exert in greater or less concen- 

 trations a toxic action upon protoplasm which is evidenced by a more 

 or less pronounced abnormality of function. In nervous or muscular 

 tissues these effects are usually evidenced by an initial increase in 

 irritability followed by a more or less rapid decrease and final loss of 

 irritability. Thus, if the foot of a decapitated frog be dipped into 

 solutions of various salts the increase of irritability of the sensory nerve 

 endings leads to a reflex withdrawal of the foot from the solution. The 

 following were the concentrations of various inorganic substances 

 which Loeb found to be effective in giving rise to this reflex: 



