37 



the chlorophyll bodies are built up. Such ors'iiuized cal- 

 cium couipounds would have a well-dertiied capacity for imbibition, 

 which would change with the replacement of the calcium by another 

 metallic element, and this altered water content must lead to a dis- 

 turbance in the structure, which must ])rove fatal if not remedied 

 in its initial stages. A peculiarity of protoplasm is that alteration of 

 the structure is soon followed b> the chemical change from tlie active 

 to the })assive moditication of its proteids. Now, when potassium oxa- 

 late acts on the inferred calcium protein compounds tliey yield in addition 

 to cal(;ium oxalate the corresponding potassium protein compounds, 

 which, on account of the different capacity for imbibition, can notphysio- 

 logically replace the calcium compound. Moieover, neither tartr.te 

 nor sulphate (which act much less energetically than the oxalate on 

 calcium compounds') atta(;k the nucleus or the chlorophyll bodies. 

 This also shows j)laiuly that it is impossible to accept the view that 

 potassium oxalate becomes dissociated in the cells and that it is the 

 free oxalic acid which, on account of its acidity, kills the nucleus, since 

 potassium nitrate would be expected to act in just the same way.- 



It will of (fourse be difficult to i)rove microchemically the formation of 

 calcium oxalate in the chlorophyll body or nucleus when ])otassium 

 oxalate is left to act upon them, since the amount of calcium in them is 

 naturally very small, Judging from the great molecular weight of tlie 

 organized proteids with which it would be combined. Moreover the 

 formation of distinct crystals of calcium oxalate would be impeded by 

 the peculiar consistency of the living structures. It was claimed that 

 in view of the highly complicated conditions in the cells the assump- 

 tion of a direct connection between a working cause and an observed 

 pathological result could not be admitted, as the latter might be sim- 

 ply the effect of primarily jjroduced " disturbances of nutrition." 

 However, this claim can not be sustained in the case of the a(;tion of 

 neutral oxalates upon the nuclei, for in the first place this proceeds 

 very rapidly in concentrations of over 1 per cent, and in the second 

 place the processes of metabolism in objects like Spiror/yra proceed 

 very slowly. 



Further observations by Migula'* deserve to be mentioned here, as 

 they demonstrate that free oxalic acid is among the most poisonous of 

 organic acids. For example, in a solution of 0.004 j)er cent of free 



• Calcinm tartrate dissolves in about 2,000 parts of water. 



^When acting on Spirogi/ra the potassium oxalate seems to pass direct to the 

 nucleus through the plasma strings and not through the tonoplast, but on the other 

 hand when potassium oxalate is contained in the cell sap of certain plants it 

 seems to be confined there by the density of the tonoplast, which also prevents its 

 dii'ect contact with the nucleus in this case. In this connection iiigula observed 

 some interesting facts with Spirogyra kept in well water to which very small quan- 

 tities of organic acids had beeu added. These were gradually oxidized in the cells 

 into oxalic acid of which some was retained as neutral oxalate in the cell sap, 

 and yielded a precipitate of calcium oxalate when placed in a diluted solution of 

 lime salts. 



3 The Influence of Dilute Acids on Alga-, (Breslau, 1888). 



