Antitoxic Action of Certain Bases 129 



excess of magnesium, then these reports are not often inconsistent, espe- 

 cially when cognizance is taken of the widelj^ different ratios of lime and 

 magnesia in different soils and of other complex relations. 



The composition of soils can be determined by means of chemical analy- 

 ses, but such analyses do not reveal the ratio in which the various mineral 

 nutrients are available to the plant. The elucidation of fundamental 

 principles from soil studies is very difficult because of the many complex 

 and uncontrollable factors existing therein. 



Loew (1901), in a review of the ratio betw^een lime and magnesia in soils 

 of different countries, states: 



" It will be seen from this review, 



"1. That the ratio of lime to magnesia ranges between wide limits. 



" 2. That in the majority of cases lime predominates over magnesia. 



" 3. That in all the instances of great fertility the soil never shows any 

 marked excess of magnesia over lime, but, on the contrary, generally more 

 lime than magnesia." 



He ^Tites also: "Lime and magnesia can exert their indispensable 

 nutritive functions only in a certain dependence upon each other. Hence 

 a certain ratio between these two nutrients will produce the most favorable 

 results, while a great excess of the one in the finest portion of the soil will 

 lead to starvation and of the other to poisonous phenomena." It is there- 

 fore clear that the determination and balancing of the available amounts 

 of magnesia and lime in the soil is necessary for successful farming on 

 apparently infertile soils. 



It was in attempting to explain the relation of calcium to magnesium 

 that Loew (1892 a) postulated the existence, in plants requiring calcium, 

 of a calcium-protein compound in which the base is not replaceable by 

 magnesium without serious injury to the protoplasm. 



According to Sirker (1908), " a topdressing with a small quantity 

 of magnesium sulphate at the rate of 10 kilo per hectar had the favourable 

 effect of increasing the harvest by 31 per cent on a plot too rich in lime 

 relatively to magnesia." 



Review of some culture experiments 

 Investigations with oats, wheat, cowpeas, and tobacco, in w^ater, 

 sand, and soil cultures, were made by May (1901). The following 

 general conclusions were reached: 



