t92t] SCHERTZ—MOTTLING gi 
those on KNO; solution died, while those on a 5 per cent sugar 
solution greened slightly.. On the .other hand, Coleus leaves 
which had mottled in the light did not green again when floated on 
any of these solutions. In the case of etiolated Coleus leaves it 
apparently is true that they do not form chlorophyll because of the 
lack of carbohydrates. The case of the mottled leaves cannot be 
explained on this basis. The catalase experiments (see later) 
show that the vigor of the mottled leaves is greatly reduced, and 
this would account for the inability of the mottled leaves to green 
again. In the case of mottled leaves carbohydrates are evidently 
not the limiting factor, for tests for carbohydrates showed that 
plenty of starch was present in the leaves. 
Microchemical analysis 
The differences between the normal green and the mottled leaf 
were determined by microchemical methods. The tests us 
were those given by Motisca and TuNMANN in their texts on 
microchemistry, and generally several tests were applied in order 
to determine the presence or absence of a substance. 
Tests for starch were made upon the two types of leaves. 
Green and mottled leaves gathered before 8 o’clock (sun time) 
showed a wide variation. The guard cells of the mottled leaves 
were especially full of starch, while some starch was found in the 
other parts of the leaves; the whole leaf had a bright blue color 
after testing with iodine. Much starch was found in all parts 
of the green leaf, and it was colored deep violet to black by the 
iodine used. In the evening, after a bright sunny day, leaves were 
collected and the amount of starch again determined. The guard 
cells of the mottled leaves were well filled with starch, and the 
other cells had much more starch than they had in the morning. 
The chloroplasts which were present appeared to be active in 
forming starch, even though no chlorophyll seemed to be present. 
Since this investigation the writer has had occasion to make some 
very accurate tests for small amounts of chlorophyll, and it is 
doubtless true that if solutions of the pigments of mottled leaves of 
Coleus had been subjected to spectrophotometric tests, chlorophyll 
would have been discovered, at least in small amounts. All cells 
