Feb. 2 ,1934 
Tissue Fluids in Cotton 
3°5 
In the second series of determinations, the differences are positive in 
all cases, and in all cases conspicuously larger than in the first series. 
They are from 4.7 to 13 times as large as their probable errors. There 
can be no reasonable doubt of the significance of these differences. 
The increase in the difference between the hybrid and the parental 
form (either Upland or Egyptian) from the first to the second series of 
determinations is from 2.8 to 6.6 times as large as its probable error. 
(Diff./Ediff. in column 8.) The difference between the hybrid and the 
parental form with respect to the ratio of specific electrical conductivity 
to freezing point lowering may therefore be confidently asserted to in¬ 
crease from the first to the second series of determinations. 
A comparison of the first and second series of determinations with 
respect to the ratio of k to A in the hybrids (Table XVII, column 5) and 
in the two cultures of the parent forms (column 6) shows that in the 
hybrid the ratio is higher in the second than in the first series of deter¬ 
minations. All of the differences are over three times as large as their 
probable errors, and may reasonably be regarded as statistically 
significant. 
In the parent forms, both Egyptian and Upland, the ratio of conduc¬ 
tivity to freezing-point depression is lower in the second than in the 
first series of determinations. Thus the parent forms are quite different 
from the hybrids in this regard. It must be noted, however, that the 
differences are small in the case of the parent plants, and can not be 
considered individually significant in comparison with their probable 
errors. 
Expressed in relative terms (Table XVII, column 10) the differences 
show that in the first series of determinations the ratio is on the average 
from —0.01 to +2.7 per cent higher in the hybrid than in either the 
Egyptian or Upland parent form. In the second series the ratio is from 
3.7 to 7.1 per cent higher in the heterozygous than in the homozygous 
plants. 
The fact that the ratio in the hybrid increases from the first to the 
second series of determinations, whereas that in both parent forms 
decreases accounts for the higher percentage difference between the 
hybrid and each of its parent forms (column 10) in the second as com¬ 
pared with the first series. 
COMPARISON ON THE BASIS OF HYDROGEN-ION CONCENTRATION 
A comparison of the acidity of the leaf tissue fluids of the hybrid 
with that of the parent form is made in Table XVIII. 
The difference column (column 8) shows at once that the hybrid is 
characterized by a larger value of P H than is that of the Egyptian parental 
form. In the comparison between the hybrid and the Upland parent 
exactly the reverse is true; the hybrid has in each series a numerically 
smaller average value of P H than has the Upland parent form. 
The differences are in all but two cases over two and a half times 
as large as their probable errors. These figures and the general con¬ 
sistency of the results for the various series are strong evidences for the 
soundness of the conclusions drawn. 
Thus the hybrid is intermediate in acidity between the two parental 
forms. 
