THE ROOT 85 
and of iron, by omitting the iron chloride. Shoots 
may also be grown in distilled water and filtered 
tap water. These experiments in water culture will 
show that, generally speaking, the absence of nitrogen 
has the most serious effect, that of phosphorus 
Ta Es Lancaster, B.Sc., photo 
Mustard plants grown in culture solutions. 
the next, and that of potassium next. Sulphur, too, 
is shown to be fairly important, while, without iron, 
the leaves become pale and sickly looking. Calcium 
does not appear to be so important as the elements 
above-mentioned, while the absence of magnesium 
