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Puant Cotors In Matrze 25 
Next in point of coloration to the seedlings given nitrogen-free nutrient 
solution and those given water alone, were the ones grown in phosphorus- 
free nutrient solution. The latter did not show red color so quickly as 
did the nitrogen-free lot, and at no time did they develop quite so much 
color. They showed, however, considerably more color at the age of one 
month than did seedlings in the complete nutrient solution. When six 
weeks old the plants of the phosphorus-free lot were relatively small, 
and had pale green upper leaves with little red color and dead lower 
leaves which still retained much red pigment. While somewhat larger 
than the plants in nitrogen-free solution and those in clear water, the 
phosphorus-free lot began wilting when about six weeks old and died 
considerably in advance of the nitrogen-free lot. Their roots showed 
early indications of injury, perhaps from toxic effects of the solution. 
Plants of all the other lots, in which one or another nutrient element 
had been omitted from the solution, exhibited little or no color reaction 
to the lack of a particular element. All of them were more vigorous 
in growth than the nitrogen-free and phosphorus-free lots, but much less 
so than the lot given complete nutrient solution. The sulfur-free lot 
for a time seemed to be developing more red, but later showed perhaps 
even less red, than the lot with complete nutrient solution. The mag- 
nesium-free lot showed prominent dark and light green stripes in the 
leaves similar to the green-striped chlorophyll pattern (Lindstrom, 1918). 
In some cases the tissue of the lighter stripes died and there was often 
some red coloration next to the dead tissue. The potassium-free lot had 
about the same amount of red color as the lot given complete nutrient 
solution, while the calcium-free lot showed less red color than any other 
lot in the test. 
It is perhaps noteworthy that in the nitrogen-free lot, and to some 
extent in the phosphorus-free lot, the new growth seemed to take place 
at the expense of the older leaves. The lower leaves first became light 
or yellowish green, then red, and finally died. That the development of 
red pigment is not necessarily connected, however, with the breaking 
down of the protoplasm, is seen in the failure of seedlings to develop 
red color in the older dying leaves of the lot in complete nutrient solution 
and of the potassium-free, magnesium-free, and calcium-free lots. In the 
calcium-free lot, growth was stopped by the death of the youngest parts, 
including the partly unrolled upper leaves, and yet these parts showed 
