May 17,1924 Leaf Tissue Fluids of Egyptian and Upland Cotton 697 
Samples of tissue were collected and the fluids extracted, and a number of 
physico-chemical constants determined 8 in essentially the manner described 
in an earlier paper (5). The chlorid content was determined by precipitating 
the chlorids as silver chlorid by the addition of a known amount of standard 
silver nitrate solution and modifying all organic substances by digesting on a 
sand bath with boiling nitric acid. The excess silver nitrate was then titrated 
with potassium thiocyanate, with iron alum as indicator. 
The samples for the series of 1920 and 1922 were preserved in sealed tubes 
and analyzed later. In all these the precipitated silver chlorid was removed by 
filtration. The analyses for 1923 were made on the fresh tissue fluids. In 
these determinations titration was made in the presence of the precipitated 
silver chlorid, as has been shown to be allowable ( 8 ) in this method. 
All results are expressed as chlorids in terms of grams of Cl per liter of tissue 
fluids. Duplicate analyses were made in a rather large proportion of the cases. 
The two determinations have been averaged to obtain the constant to be used to 
represent the plants unless there was some evidence that one of the two analyses 
was more accurate than the other. When one sample contained 10 cc. whereas 
the other contained less than 5 cc. the constant determined from the larger 
sample.has generally been taken. 9 
PRESENTATION OF RESULTS 
Only one pair of determinations of chlorid content are available for cotton 
grown in 1920. These seem to indicate a higher concentration of Cl in the 
Egyptian than in the Upland types. 
Table I .—Chlorid content of the leaf tissue fluids of Egyptian and Upland cotton 
grown in 1920 
Variety of cotton 
Number of 
sample » 
Gm, of 
chlorids 
(Cl) per 
liter 
Pima Egyptian, ____ ___ 
(1) 
(2) 
(1) —(2) 
6.29 
4.43 
+ 1.86 
Acala Upland_ __ ... .. 
a The sample numbers are the same as those used to designate the determinations given elsewhere (5). 
In each experiment except that for 1920, relatively large numbers of analyses 
were made on samples so taken that each determination based on tissues col¬ 
lected from Egyptian plants was provided with a control sample taken from 
Upland plants grown under as nearly as possible the same conditions. 
The comparisons for these large series may be most crucially made by means 
of statistical constants and their probable errors. The differences between the 
varieties compared are, however, sufficiently large that they may be brought 
out by means of a mere tabulation of the analyses. 
8 These will be considered elsewhere in relation to another group of problems. 
9 We have to thank Supt. C. J. King for many courtesies which facilitated our work at Sacaton. George 
J. Harrison was responsible for the making of the rather complicated plantings and for the superintendence 
of the cultures throughout the season. We are greatly indebted to G. O. Burr, Charles W. Crane, R. D. 
Evans, A. II. Johnson, W. B. Sinclair, and A. T. Valentine, field assistants in 1922 and 1923, for their large 
part in the collection and preparation of the samples for analj'sis. 
