39 



CAN CALCIUM IN PLANT CELLS EE REPLACED BY STRONTIUM! 



It lias loug been recognized that calcium salts can not be replaced by 

 potassium salts or sodium salts. Were it a well-founded hypothesis 

 that calcium salts serve only for certain phases of metabolism and are 

 not connected with more important properties of the protoplasm itself, 

 then there might be taken a plain chemical view of the matter, that is, 

 that the action of the bivalent elements is often different from that of 

 the monovalent elements. Thus, for example, dextrose yields saccharin^ 

 when treated with lime, but not when treated with potassa (Kiliani); 

 calcium carbamate yields calcium cyanamide ni)on heating, while jiotas- 

 sium carbamate yields potassium cyanate (I)rechsel); barium dibrom- 

 succinate yields monobrommaleic acid on boiling of the aqueous solu- 

 tion, while the sodium salt yields monobrommalic acid. 



It is certainly not the bivalent character of calcium, however, tliat 

 determines its i)hysiological value, for in that case barium or strontium 

 might fulfill the same office, which is impossible. The inability of 

 barium to do this might be explained by the most characteristic ]»rop- 

 erty of soluble barium salts, which is to precipitate sulphuric acid from 

 even high dilution of sulphates, hence in plants the assimilation of 

 sulphur from sulphates would become an impossibility. However, it 

 would still be difficult to explain why barium salts are i)oisonous ibr 

 animals, and also why strontium salts can not replace calcium salts 

 in either plants or animals.^ 



The more intimate the connection between the functions of the lime 

 and the vital properties of the cells, the more difficulty will naturally 

 be encountered in an endeavor to substitute strontium for calciun), and 

 experiments made in this connection argue against the possibility of 

 the substitution. The writer made some experiments with an alga 

 {Spirogyra) in 1892 which demonstrated that although this alga can 

 remain healthy for several weeks at the ordinary temperature in a culture 

 solution containing strontium nitrate in place of calcium nitrate, its 

 further growth is nevertheless impeded, and moreover, that there is soon 

 a noxious influence at a higher temi)erature (28° C). Thus, for example, 

 many cells died when kept at 28° C. in a solution of 0.3 per cent stron- 

 tium nitrate, but this was not the case in a 0.3 per cent solution of 

 calcium nitrate. This conclusion has been essentially confirmed by 

 Molisch, who observed the interesting fact that the cell plate in the 

 l^rocess of cell division is not properly formed when strontium salts are 

 pj'esent in place of calcium salts. This occurs even when a small 

 amount of a calcium salt is present, in which case the injurious effects 

 of the strontium salt are not entirely x>revented. The cell plate is the 

 result of the work of the nuclear spindle, and the supposition that the 

 cause of this defective work is attributable to a diseased condition of 

 the nucleus seems justifiable. If the lime were not concerned in the 



'This product is uot the sweet saccharin of commerce. 



'^ Only certain enzym actions form exceptions, as liertrand has shown for pectase. 



