oct. i 5,1925 Translocation of Food Materials of Wheat Seedlings 729 
Therefore the method as described by McCool and Millar (31) was 
followed in the determination of the freezing point of the ground 
tissue. The ground paste was placed in the freezing tube in such a 
way as to press gently around the bulb of the Beckman thermometer. 
The only precaution necessary to use in making the determinations 
in this way is to keep the freezing bath at about 4° C. Experiments 
on older plants indicate that the depression is slightly greater with 
the tissues than with the extracted juices, and this confirms the work 
of McCool and Millar (31). (Data are given in Table II.) 
Table II. — Depression of the freezing point of the juice and ground tissue of plants 
Age of 
Depression in 
degrees 
Increase 
in depres¬ 
sion in 
ground 
tissue 
plants 
Juice 
Ground 
tissue 
Days 
5 
0.75 
0.76 
0.01 
.715 
.765 
.05 
6 
.61 
.705 
.095 
,62 
.710 
.090 
Since the depression is somewhat greater for ground tissue than for 
extracted sap, the reading for the 2-day-old plants shows a depression 
slightly in excess of what we would expect. 
In all cases except the 15-day stage with four samples, the results 
given are from the average oi determinations of five sets of plants 
grown separately, and no more than two determinations were made 
in any one day. 
Comparisons were made of the freezing-point depression of the 
sap of roots, plumules, and entire plants. The data are submitted 
in Table III. 
Table III. — Comparison of the freezing-point depression of the sap of roots , 
plumules , and entire plants 
Age 
of 
Depression in 
degrees 
Average 
Entire 
plants 
plants 
Plumules 
Roots 
Days 
10 
0.545 
0.260 
0.4025 
0.39 
.545 
.250 
.3975 
.385 
15 
.600 
.255 
.4275 
.43 
.575 
.250 
.4125 
.43 
The plumules have a depression nearly twice as great as that of the 
roots. If reference is made to Table IV it may be observed that the 
plumules have more soluble materials and less water than the roots. 
This would account for the difference in the freezing points. Averag¬ 
ing the depression of the roots and plumules, the depression is practi¬ 
cally the same as for the entire plant. This is to be expected, as the 
green weights of the roots and tops differ by ofily a little. 
imm 
CEREAL INVESTIGATIONS. 
