Bouyoucos, Transpiration of Wheat Seedlings as Affected etc. 
7 
were carefully noted. It was observed that, as a general rule, 
the seedlings grown in the higher densities always made, at the 
beginning, a much slower gi’owth than those in the lowr concen- 
trations. Indeed, it always appeared that the rate of growth 
increased as the density decreased. After the first fonr or fiye 
days, however, this Order was reversed; the plants in the higher 
densities began to grow yery rapidly and the rate or magnitnde 
of growth became decidedly proportional to the concentration. 
In connection with the aboye Observation, it might also be 
inentioned, that the germination of the seeds was also retarded 
by the higher densities. The time reqnired to sprout was propor¬ 
tional to the concentration. and the difference in time between 
the two extremes, was from one to two days. 
At the termination of each experiment a carefnl examination 
was always made of the total growth and of the general appearance 
of the plants, including both the tops and the roots, in all three 
kinds of cultures. In the case of the tops, it was obseryed that 
they were healthy, yigorous, and their total growth always tended 
to increase with the increase in density. The roots also always 
appeared to be healthy, yigorous and turgid, and their total weight 
to be proportional to the actnal weight of the tops. As to the 
latter relation, several attempts were made to confirm it quanti- 
tivelv by determining the dry weight of the roots and then com- 
paring this witb the dry weight of the tops. It was found, however, 
that this comparison was not reliable, becanse the roots in the 
different densities contained yarious amonnts of fine sand particles 
which were practically impossible to wash out. In view of this 
difficulty, the determination of the dry weight of the roots had to 
be abandoned, and therefore, the relation of the roots to tops, 
roots to transpiration, and roots to density, all of which would 
have been of great interest, could not be ascertained. 
The dry matter of the tops was determined by drying them 
in a drying oven at the temperature of boiling water for about 
10 hours and then after cooling, they were weighed on a Chemical 
balance. The total dry matter was then compared with the total 
transpiration, and the amount of water reqnired to produce one 
gram of dry substance, calcnlated. 
Mention has aiready been made that this line of the research 
involved fiye series of solution cultures, nine series of sand cultures, 
and fonr series of soil cultures. Inasmuch as all the different 
series within the same culture received practically the same treat- 
ment, and show almost the same Order of results, it warrants ns 
in arranging their individual results, in averages. The main con- 
clusions will, therefore, be drawn from these averages. These 
data are given in the following tables. Each table is accompanied 
by a diagram to illustrate its salient facts in a graphical form. 
It is evident from the foregoing talbes and diagrams that the 
different densities of the complete nutrient solution have a very 
significant effect upon the transpiration of the wheat seedlings, 
and that this effect manifests itself in all three of the different 
