122 BOTANICAL GAZETTE [FEBRUARY 
nitrogen sources such as asparagin, peptone, and ammonium 
‘nitrate, greened, and when potassium nitrate was used it became 
pale or colorless. If Stichococcus were grown in the light and fed 
upon rich organic nutrients (maltose, glucose), it lost its chlorophyll. 
If the colorless algae which had been growing in the dark were 
placed in the light and given potassium nitrate as riutrient, they 
regained their normal color and the chromatophores became normal 
again. He did not know whether the chromatophores were built up 
anew or not. ARTARI also found that when he placed the colorless 
algal cells on a nutrient solution which contained either asparagin 
or ammonium nitrate, and placed them in the dark, the algae 
greened again. : 
TABLE XXX 
COMPARISON OF GREEN AND YELLOW PIGMENTS IN LEAVES 
HEMP PLANTS UNDER DIFFERENT TREATMENTS 
Process Chlorophyll Carotin 
Intense manuring.............. 100 100 
Compl Ae MANNE... ss... 74 90 
Nutrients lacking nitrogen...... 38 57 
Nutrients lacking phosphates. . . 71 80 
Nutrients lacking potassium... . 66 72 
Nutrients lacking calcium...... 72 go 
No nutrients added............ 53 71 
The effect of the various nutrient elements is perhaps best 
described by VILLE (51). He experimented upon the effect pro- 
duced on the color of many field plants by a deficiency in nitrogen, 
calcium, phosphate or potassium, and no manuring. He found 
that nitrogen affects chiefly the color of the plants, and if it is 
deficient the plants become brown, while if the dose of nitrogen 
is increased or diminished, the color increases or diminishes accord- 
ingly. He made crude extracts of the leaves of hemp and com- 
pared the green and yellow pigments in them. Table XXX shows 
the results of VILLE’s experiments. 
The Coleus here studied seems to be on the verge of nitrogen 
starvation at all times under ordinary greenhouse conditions. It 
is only with considerable nitrate additions that the nitrogen supply 
of the leaf can be maintained sufficiently to avoid chlorophyll 
