go BOTANICAL GAZETTE [FEBRUARY 
as the chlorophyll disappeared between the veins. Leaves and 
stems of plants grown in culture solutions deficient in phosphorus 
were purplish green. This color is apparently due to the presence 
of a purplish colloidal substance (perhaps a result of the decom- 
position of the chlorophyll) intermixed with the chlorophyll. 
Oat plants grown in solutions weak in nitrogen produced narrow 
purplish green leaves. Microscopical examination showed the 
chloroplasts more or less disorganized. A deficiency in phosphorus 
or in nitrogen produced a markedly unfavorable effect by causing 
a great decrease in the vegetative growth.. : 
Jost (27) asserts that two Helianthus plants growing to maturity 
in three months used 1.4 gm. of KNO,. These experiments with 
Coleus plants showed that one Coleus plant growing in soil in a 
3-inch pot used the equivalent of 1 gm. of KNO,, in addition to the 
nitrate which was in the soil, and then did not reach maturity. 
This shows that Coleus, being a plant much smaller than the sun- 
flower, seems to use large quantities of nitrate. During the course 
of the experiment, if the nitrogen supply was discontinued at any 
time, the plants began to mottle at the margin of the leaves, but 
the leaves greened when the supply was again added. This shows 
that the plant was using the nitrate which was added to the soil in 
the pot. Burp (9) computed from the crop the amount of nitrate 
one barley plant used, and found that about 1.1 gm., calculated 
as potassium nitrate, was sufficient to bring the plant to maturity. 
PALLADIN (40) states as follows: 
. Carbohydrat tial to the f tion of chlorophyll. Plants fallinto 
two groups according to the carbohydrate content of their etiolated leaves. 
In one group (for example, barley) the etiolated leaves contain much soluble 
carbohydrate material, while in the other group (as beans and lupines) the 
etiolated leaves contain very little carbohydrate. If etiolated leaves of these 
plants are removed and floated upon water in the light, those of barley become 
green, while almost all the bean leaves and all those of lupine remain yellow. 
If the latter are floated, not upon water but upon a saccharose or glucose solu- 
tion, then they also become green. 
The writer conducted experiments with Coleus leaves similar to 
these of Pattapin. Young Coleus plants were kept in darkness 
until the leaves became etiolated. These etiolated leaves of 
Coleus when floated on distilled water in the light remained yellow, 
