468 Mr Lawrence Balls, Specific Salinity in the Cell Sap, ete. f 
First-year plants in the salted cages gave 0:90 and 1:09, while 
second year plants (rattoons) in the cages gave 1°53 and 1°86, and 
earlier analyses from the same plants gave 1:08, 1:36, 1-47, | 
eg, gs . 
There are thus variations in the content of a pure strain, | 
directly with, but not proportionate to, the variations in salinity | 
of the soil. : 
Pure strain No. 310. It is interesting to note that this: 
strain is agriculturally useless near Cairo, but flourishes in the 
salter lands of the cooler northern Delta, where No. 77 isi 
useless. 
j : t 
Several plants were growing so close to plants of No. 77 | 
that their roots were interlacing. The analyses from three such) 
pairs, two samples from each, are given below: 
Mean Ratio 
No. 310 0:96 1:17 0:90 1:04 1:30 1°52 1:15 100 
No. 77 0:76 0:76 0°80 0:62 0:90 1:09 0:82 71 j 
Similar indications were found with other strains, that a 
definite specific difference in salinity existed between them. 
These numerical differences might be due to differences in 
the leaf-structure, but there is no evidence in favour of such 
a view. The probable error of dry-weight determinations from) 
equal leaf-areas of 15 sq. cm. on all kinds of Egyptian cotton is) 
only +4 °/,. 
It is interesting to note that the highest figure recorded for 
American Upland cottons grown in the U.S.A. that I have been | 
able to find, is only 0:1 °/,, while a few determinations at Giza on) 
Russell and King varieties ranged from 0:37 to 0°81. | 
Conclusions. Egyptian cotton growing in typical field crop) 
has a salt content which indicates a concentration of 0:3 °/, NaCl’ 
in the cell-sap. } 
This concentration varies with the salinity of the soil, though _ 
not proportionately. | 
It also varies with the particular pure strain or variety of 
Egyptian cotton employed. 
Plants of two Egyptian strains growing with interlacing root-| 
systems may show differences of as much as 10:7 in the salinity 
of their cell-sap. / 
The latter fact may have some utility in future breeding of| 
strains for the salty lands of the Northern Delta of Egypt, where: 
large schemes of reclamation are in progress. | 
um peruvianum, &c.) may be classed | 
Egyptian cotton (Gossypo 
as a facultative halophyte. 
