1910) REED—TRANSPIRATION AND GROWTH OF WHEAT 87 
ing the experiment; the green weight was found by cutting the plants 
at the surface of the soil in the pot and weighing them immediately, 
before any material loss of water occurred. _ If the dry weight was 
to be recorded, the plants from each set of pots were placed in unsealed 
paper envelopes and slowly dried at room temperature. 
Many experiments described in this paper were carried out in 
water cultures, in which the aqueous extract of a soil, or a salt solu- 
tion was used as the culture fluid. The water cultures were prepared 
and conducted according to the methods described by LivincsTon 
(8) and Scuremer and REEp (14), in which 10 wheat seedlings 
are installed in each culture jar. The culture jars employed in this 
work were saltmouth green flint glass bottles of 240°° capacity. 
Flat corks which fitted the mouths of these bottles were notched by 
cutting ten vertical wedges from their lateral surface. Each wedge 
was about 4™™ broad and 5 or 6™™ deep, and extended from top to 
bottom of the stopper. The cork wedges, after being cut out, were 
truncated at their inner angles by the removal of enough cork to allow 
them to be replaced in position after a seedling had been placed in the 
inner apex of the space from which each wedge had been cut. The 
stem of the seedling was placed in its groove, with the seeds just below 
the lower surface of the cork, and the wedges were pressed into 
position. Each wedge should exert sufficient pressure on the seedling 
to hold it in place when the stopper is inserted in the bottle. After 
all were in position, a rubber band was placed around the stopper 
to hold the wedges in place, and the stopper was then pressed firmly 
into the neck of the bottle which contained the culture fluid. The 
cultures prepared by this method afford practically no opportunity 
for the direct evaporation of water from the bottles. Practically all 
the water lost occurs as transpiration from the plants grown in the 
cultures. To keep conditions equable, the solution in the bottles 
should be renewed or the bottles replenished with distilled water every 
four or five days. 
Since the water loss is only through the plants, the cultures may 
be weighed at each change, and the sum of the losses recorded may 
be taken as the total transpiration of the 10 plants for the period of 
the experiment. This total water loss being proportional to the leaf 
area when wheat is used, it is consequently a practical method for 
