Oct. 1, 1925 
Sulphate Content of Leaf-Tissue Fluids of Cotton 
655 
Table I .—Frequency distribution of sulphate content (in terms of grams of SO 4 
per liter of fluid) in leaf-tissue fluids of Egyptian and Upland cotton grown 
under irrigation at Sacaton f Ariz., in 1922 and 1928 
These determinations show that while the sulphate contents of 
the two types of cotton are highly variable they are <piite different, 
that of the Upland type (Meade and Lone Star) being apparently 
significantly higher than that of the Egyptian type (Pima). 
The variability of the sulphate content is presumably due to the 
influence of substratum heterogeneity which has been shown to be 
a practically universal characteristic of experimental fields ( 2 , 3 ). 
Illustrations of its influence on the tissue fluids of cotton are sufficiently 
developed in preceding papers (4, 5 ). Since the determinations on 
the two types were made in pairs, the true relationship between the 
concentrations may be shown best by a double-entry arrangement in 
tables in which the sulphate content of the two’ forms are shown on 
two axes. The form of table is identical with that employed in the 
writers’ discussion of chloride content ( 5 ). 
Table II presents the results for the first comparison of Pima and 
Meade plants (1922). Tables III and IV give the results for the first 
and second series of determinations on the Pima Egyptian and Lone 
Star Upland cultures of 1923. 
