62 PHYSIOLOGICAL ROLE OF MINERAL NUTRIENTS. 



diminished and mineral nutrients added, the composition of the main 

 solution being — 



Per ruille. 



Calcium nitrate 0. 10 



Calcium sulphate 01 



VIonopotassiuni phosphate 01 



Dipotassium phosphate . . .-. 01 



Beryllium sulphate . 10 



In this solution Spirogyra threads were still normal and healthy 

 after three weeks, but had not grown to any noticeable extent. 

 In another experiment the following solution was prepared: 



Per ruille. 



Calcium nitrate 0. 25 



Calcium sulphate 10 



Monopotassium carbonate : 1. 00 



Monopotassium phosphate 05 



Ferrous sulphate Trace. 



One-half of this solution received 0.2 gram magnesium sulphate and 

 the other half 0.2 gram beryllium sulphate. Very soon a slight tur- 

 bidity, followed later by a floeeulent precipitate, was noticed in the 

 beryllium solution, while the control solution remained absolutely clear. 

 Into both flasks a trace of a PalmelZa culture, with some Diatoms. 

 was now introduced. After four weeks it was found that the Diatoms 

 had multiplied to a great extent in the control solution, but not one 

 could be observed after repeated microscopical examinations in the 

 beryllium solution. The Pblmella, however, was well developed in 

 both flasks. This might seem to indicate that such a simple alga form 

 as Palinella could utilize beryllium salts in place of magnesium salts, 

 at least when offered in a favorable culture solution: but slight traces 

 of magnesia might have been furnished by the glass vessel. 



To determine the effects of beryllium on fungi an experiment was 

 made by Molisch. the culture solution used containing — 



Per mille. 



Ammonium acetate 20. 00 



Beryllium sulphate 40 



VIonopotassium phosphate 04 



Ferrous sulphate 01 



There was no development whatever in this solution when spores of 

 Penicillium were inoculated, but upon the addition of 0.02 per cent 

 magnesium sulphate 78 milligrams of fungous mass was produced after 

 nineteen days. 



Notwithstanding the close chemical relations between beryllium 

 and magnesium there must exist such chemical differences that the 

 inability of beryllium to physiologically replace magnesium can be 

 easily explained. As the text-books on chemistry fail to give minute 

 comparisons of the chemical behavior of soluble beryllium and mag- 

 nesium salts toward phosphates, the writer has made a few tests in 



