59 



of sufficient lime the poisonous action of strontium salts ui)on 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 intelligible 

 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 (tectonic). Indeed, oxalates constitute a general 

 poison for all kinds of animals.' The writer has demonstrated that in a 

 0.5 per cent solution ot neutral potassium or sodium oxalate Rotatoria, 

 Copepoda, and aquatic AseUids die in thirty to fifty minutes, leeches 

 and Planaria succumb a little later, and finally Ostracode.s and larvjc of 

 insects are killed. Injusoria, Fhujellata, and Amocbw 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 i)oisonous 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 iuHammaticm of the kidneys, and 

 others believed in a decomposition of the oxalic acid with the i)roduc- 

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

 paralysis of the vasomotoric center jMunted plaiidy to another cause.- 



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 nnclein. It also makes it perfectly clear why 

 on the one hand magnesium salts become poisonous in the absence of 

 calcium salts, and why on the other hand the absence of magnesium 

 salts in an otherwise complete culture solution leads to a gradual stop- 

 page of all further development, and to final inanition. The formation 

 of the nuclei and plastids requires calcium as well as magnesium salts, 



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

 heart have been noticed after feeding cattle vrith vegetables containing soluble 

 oxalates, such as leaves of the sugar beet. 



^The fact that badly healing sores are produced when open wounds come in con- 

 tact with oxalate solutions, a fact long known to photographers, deserves particular 

 mention. 



