20 R. A. EMERSON 
of the excess of water. Wet soils in spring are cold soils, and if the wet 
areas are of considerable extent the air above them is doubtless somewhat 
cooler than that above drier soil. It has been frequently observed 
that young plants which show much color during a cold spring 
show considerably less in the leaves developed after the weather has become 
warmer. Young plants of early-planted maize sometimes have more 
color than plants that are started later. Moreover, full-grown plants 
from late plantings often develop more color in the cool weather of autumn 
than similar plants that mature in the warm weather of late summer. 
It seemed important, therefore, to study the effects of various tempera- 
tures on color development. 
The same color types and the same stocks—in one test the identical 
plants— used in the soil-moisture test were grown in the greenhouse under 
diverse temperatures. Altho both rich and poor soils of diverse water 
content were used, the comparisons noted here were made between plants 
in the same kind of soil and with practically the same soil-moisture con- 
ditions. Two lots were grown during the winter of 1913-14 and two dur- 
ing the following summer. During the winter, one lot was kept in a warm 
house at temperatures varying from about 18° to 26° C., and one was 
kept in a cool house at temperatures varying normally from about 7° to 
15° C. but during a part of the test dropping at night to 1°or 2°C. Both 
lots were exposed to the full winter sunlight of the houses. During the 
summer test, one lot was kept as cool as possible by partial shading and 
free ventilation, the temperatures ranging from about 15° to 40° C. but 
occasionally exceeding these limits, and the other lot was kept in an 
unshaded house the ventilators of which were never opened. The night 
temperatures of the closed house averaged not more than one degree 
higher than those of the open house, but the maximum day tempera- 
tures in the closed house varied usually from about 44° to 50° C. and on 
three consecutive days reached 55° C. This extreme heat killed most 
of the plants grown in rich soil but did not seriously injure those in poor 
soil. Of course the relative humidity, as well as the intensity of the 
light, was materially different for the closed and the open house. 
As a result of these tests, no final differences in the development of 
color in any of the color types were observed between the lots grown 
at the very diverse temperatures. Of course differences were observed 
at certain times, but they are readily accounted for by the facts that the 
