506 Reed . — The Vahie of Certain Nutritive Elements 
Multiflorus ) which he employed displayed, when grown in the absence of 
calcium, interruptions in the translocation of carbohydrates. When mag- 
nesium was lacking the chlorophyll bodies became unhealthy, and, as 
a result, the plants possessed an etiolated appearance. 
Loew (’92) ascribed a highly important function to calcium. He 
regards calcium as one of the important mineral bases which enter into the 
constitution of the proteids composing the cell nucleus and chlorophyll 
bodies. According to his interpretation these proteids take up magnesium 
in the absence of calcium, and the resulting magnesium-proteid compound 
has not the same well-defined capacity for imbibition and other processes 
which the calcium-proteid bodies possess. Hence the harmful effects 
observed when plants grow in a calcium-free medium which contains mag- 
nesium. Loew verified the observations of Boehm and von Raumer that 
solutions of pure magnesium salts have a toxic action, and ascribed it also 
to the harmful substitution of magnesium for calcium in the proteids. 
Bokorny (’95) repeated and confirmed many of Loew’s experimental data. 
Unfortunately this theory fails in the case of a group of plants which form 
considerable amounts of proteid, viz., the Fungi. It is well known that the 
members of this group of plants are able to reach maturity and form repro- 
ductive bodies in the entire absence of calcium. More conclusive evidence 
would seem to be needed to establish the calcium-proteid theory. 
In their study of Phaseolus plants grown in water cultures, von Portheim 
and Samec (’05) obtained results which afford some support for the calcium- 
proteid theory. They found by analysis that normal plants contained 
much more calcium than magnesium ; but plants grown in solutions lacking 
calcium had a much greater proportion of magnesium than the normal 
plants. In pathological conditions induced by the absence of light, the 
amount of magnesium in the plant was nearly equal to the calcium, although 
the plants were supplied with a complete nutrient solution. The fact that 
the plants deprived of calcium took up more magnesium strengthens Loew’s 
assumption of the calcium-proteid compound, yet it will require further 
investigation to determine whether this additional magnesium may not find 
use in other ways in the plant. Haselhoff (’93) showed that strontium was 
unable to replace calcium in water cultures of Vicia and Zea. Loew (’98) 
and Suzuki (’00), have also shown that the functions of calcium cannot be 
performed by strontium or barium. 
The neutralizing action of calcium in the synthesis of proteids has 
been taken up anew by Yermakov (’05) in connexion with the assimilation 
of nitrates. This author assumed that since ammonia and oxalic acid are 
formed when nitric acid acts upon glucose, that a similar reaction might 
occur in the synthesis of proteid in the plant. If this assumption were 
true, the oxalic acid formed would not be neutralized in the absence of 
calcium salts, and being injurious to the plants would hinder the assimi- 
