Special Functions and Relations 



185 



In general, the magnesium compounds are particularly 

 toxic to the higher plants. Corn is an apparent exception 

 to the rule, as are also most fungi and some algse. On 

 account of the fact, then, that magnesium compounds are 

 so generally harmful when alone, or in relative excess, it 

 is of special interest to note in some detail the relation of 

 this element to other bases. 



102. The relation of calcium to magnesium. The 

 toxic action of magnesium and the effect of calcium in 

 modifying it were established by Von Raumer in 1883 ; 

 but the most important work in outlining and directing 

 attention to this field with respect to plants was done by 

 Loew and his associates. There is at present a mass of 

 data available both on the plant and on the animal side. 

 As a general result of all the work on the higher plants it is 

 now clear that when magnesium is injurious, the presence 

 of calcium in a certain ratio (variable for the plant) de- 

 stroys this toxicity entirely. To explain this relation Loew 

 formulated his theory of the existence of a calcium-protein 

 body as previously outlined (section 95). 



