68 PHYSIOLOGICAL ROLE OF MINERAL NUTRIENTS. 



made, and as a result great softness of the bones and rachitic altera- 

 tions were soon obvious. Weiske arrived at the same conclusions and 

 refuted the contrary opinions of Papillion and Ktfnig. In the presence 

 of sufficient lime the poisonous action of strontium salts upon animals 

 is weak. 



The writer's hypothesis as to the functions of lime salts makes the 

 poisonous action of soluble oxalates upon animals also more intelligi- 

 ble than it has been heretofore. The chief property of oxalates is to 

 transform the calcium of calcium compounds into calcium oxalate. If, 

 therefore, the nuclei of the cells contain calcium protein compounds in 

 their organized structure, the removal of this calcium and its replace- 

 ment by the sodium or potassium of the oxalate applied must alter 

 the capacity of imbibition, and thus cause fatal disturbances of the 

 organized structure. Indeed, oxalates constitute a general poison 

 for all kinds of animals/' The writer has demonstrated that in a 0.5 

 per cent solution of neutral potassium or sodium oxalate Rotatoria, 

 Copepoda, and acquatic Asellids die in thirty to fifty minutes, leeches 

 and Planaria succumb a little later, and finally Ostracodes and larvae of 

 insects are killed. Infusoria, Flageilata, and Amoebm were found to be 

 dead in this solution after fifteen hours. Even a 0.1 per cent solution 

 of sodium oxalate will kill some of the organisms named, such as Cope- 

 poda and Rotatoria. The poisonous action for vertebrates was known 

 long ago, but the explanations were not entirely satisfactory. Some 

 authors sought the cause in the obstruction of the vessels of the kid- 

 neys with calcium oxalate and in inflammation of the kidneys, and 

 others believed in a decomposition of the oxalic acid with the produc- 

 tion of the poisonous carbonic oxid, but the irritation and the final 

 paralysis of the vasomotoric center pointed plainly to another cause. 6 



FINAL REMARKS. 



The writer's deliberations have led him to conceive the probable role 

 of calcium and magnesium salts in the living cells. This view is in 

 full accord with various facts for which in former times no satisfactory 

 explanation was reached. 



It is now clear why magnesium is more movable in plants than cal- 

 cium, and, further, why the calcium content increases with the mass of 

 nuclear substance and of chlorophyll bodies, and why magnesium salts 

 increase wherever phosphoric acid is in increased demand for the pro- 

 duction of lecithin and nuclein. It also makes it perfectly clear why, 



« Noxious effects on the bones and kidneys and sometimes on the activity of the 

 heart have been noticed after feeding cattle with vegetables containing soluble 

 oxalates, such as leaves of the sugar beet. 



6 The fact long known to photographers, that badly healing sores are produced 

 when open wounds come in contact with oxalate solutions, deserves particular men- 

 tion. 



