Feb. a, 1924 
Tissue Fluids in Cotton 
323 
Meade seed; 5.257 in the Pima as compared with 5.302 in the associated 
Acala plants. In the second series of determinations the differences are 
of about the same order. 
A comparison of the sap properties of the hybrids between Pima 
and Meade (P x M) with those of the two parents gives the following 
results: 
The osmotic concentration of the tissue fluids of the hybrid is lower 
than that of either of the parent types. 
When the hybrid is compared with parental cultures grown from self- 
fertilized seed, the hybrid has an osmotic concentration 3.87 per cent 
lower than that of the Meade parent and 7.36 per cent lower than that of 
the Pima parent in the first series of determinations, and 6.18 per cent 
lower than that of the Meade parent and 12.4 per cent lower than that of 
the Pima parent in the second series of determinations. 
When the hybrid is compared with the parental forms grown from 
bulk seed, the hybrid has an osmotic concentration 4.34 per cent lower 
than that of the Meade parent and 4.75 per cent lower than that of the 
Pima parent in the first series of determinations, and 8.18 per cent lower 
than that of the Meade parent and 12.3 per cent lower than that of the 
Pima parent in the second series of determinations. 
Since the Upland cotton has a lower osmotic concentration than the 
Egyptian, the difference between the hybrid and the Upland type is of 
necessity smaller than that between the hybrid and the Egyptian type. 
The difference between the hybrid and the parent forms is greater in the 
samples taken later in the season. 
The specific electrical conductivity of the hybrid is in all cases lower 
than that of either of the parent types. In the first series of determina¬ 
tions the conductivity of the hybrid tissue fluids was 4.35 per cent lower 
than that of the Meade parent and 7.84 per cent lower than that of the 
Pima parent when the two parents were grown from self-fertilized seed. 
The hybrid was 1.53 per cent lower than the Meade parent and 4.39 per 
cent lower than the Pima parent when the parent forms were grown 
from bulk seed. In the second series of determinations the percentage 
differences range from 0.33 per cent in comparison with the self-fertilized 
Meade parent to 9.11 per cent in comparison with the Pima parent from 
bulk seed. 
In general, the differences between the parent and the hybrid forms 
are greater in the determinations made later in the season. 
Since the conductivity is lower in the Upland than in the Egyptian 
type, the difference between the constant for the hybrid and that for 
the Upland parent form is smaller than that between the hybrid and the 
Egyptian parent type. 
The ratio of specific electrical conductivity to freezing-point depres¬ 
sion, k/ A, is generally but not invariably higher in the hybrid than in 
the parent forms. In the first series of determinations the ratios are 
sometimes higher in the hybrid and sometimes higher in the parents. 
In the second (later) series, the hybrid gave a ratio from 3.7 to 7.1 per 
cent higher than the parent forms. The differences are, therefore, 
larger and more clearly significant in comparison with their probable 
errors in the later than in the earlier series of determinations. 
The hydrogen-ion concentration of the hybrid is higher than that of 
the Egyptian parent, but lower than that of the Upland parent. Thus 
the hybrid tissue fluids are less acid than those of the Pima parent, but 
