338 H. W. Turpin 
Fig. 02. MILLET CROPS SIX WEEKS AFTER SEEDING, ON THE TWO SOILS HAVING HIGH AND 
LOW INITIAL CONTENTS OF CARBON DIOXIDE, RESPECTIVELY 
Close view, showing details 
The crop was planted on July 1. Within three weeks after planting, 
the crop on each can had been thinned out until forty plants remained. 
The number of plants to a pot was reduced in the next week to thirty. 
At first the samples were taken twice a week, as in the case of experi- 
ment 1; but later —from the middle of August — when the crop was 
making very rapid growth, samples were taken every day. Toward the 
end of August the samples were taken every other day. As in experi- 
ment 1, the moisture in the soil was maintained at 30 per cent (oven- 
dry basis). 
At the time when the experiment was discontinued, the plants were 
completely headed. In the case of series 1 (soil previously cropped to 
oats) the plants were beginning to show signs of maturing; in series 2 
(soil previously bare), however, the grain was still between the milk 
stage and the dough stage. 
The crops on series 1 and 2 were identical in all details until a few 
days after heading. This may be seen in figures 52 to 55. Thereafter 
the plants in series 2 maintained their dark green color, while those in 
iota 
