CALCIUM AND STRONTIUM. 47 



(Kiliani); calcium carbamate 3delds calcium cyanamide upon heating, 

 while potassium carbamate yields potassium cyanate (Drechsel); ba- 

 rium dibromsuccinate yields monobrommaleic acid on boiling of the 

 aqueous solution, while the sodium salt }delds monobrommalic acid. 



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

 determines its physiological value, for in that case barium or stron- 

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

 of barium to do this might be explained by the most characteristic 

 property of soluble barium salts, which is to precipitate sulphuric 

 acid from even high dilution of sulphates, hence in plants the assimi- 

 lation of sulphur from sulphates would become an impossibility. 

 However, it would still be difficult to explain why barium salts are 

 poisonous for animals, and also why strontium salts can not replace 

 calcium salts in either plants or animals. a 



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 calcium, 

 and experiments made in this connection argue against the possibility 

 of the substitution. The writer made some experiments with an alga 

 (Spirog'yra) 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 temperature (28° C). 

 Thus, for example, many cells died when kept at 28° C. in a solution 

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

 per cent solution of calcium nitrate. This conclusion has been essen- 

 tially confirmed by Molisch, who observed the interesting fact that 

 in the process of cell division the cell plate is not properly formed 

 when strontium salts are present 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 

 prevented. 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 most intimate working of the 

 nucleus the phenemenon in question would hardly be intelligible. 



Similar experiments with beans and maize were inaugurated later 

 on by Haselhoff, & but he offered calcium and strontium salts together 

 in the beginning and gradually diminished the lime in the culture 

 solution. The plants, however, very probably made use of the occa- 

 sion to store up a certain amount of lime, which they may have used 



a Only certain enzyme actions form exceptions, as Bertrand has shown for pectase; 

 here also barium or strontium salts cause a precipitate. 

 ^Landw. Jahrb., Vol. XXII, p. 853. 



