276 Journal of Agricultural Research voi. xxvn, No. s 
in this paper into atmospheres by the use of a published table (24), as 
we have done in a few cases. 
Conductivities have been expressed in reciprocal ohms or mhos. 
At the time of making these determinations we were unacquainted 
with the methods suggested by Mason (45) for estimating the influence 
of viscosity upon electrical conductivity. The conductivities given are, 
therefore, the raw values wholly uncorrected for the resistance of the sap. 
Inasmuch as the biological forms considered do not show large percentage 
difference in freezing-point depression, this fact probably does not in¬ 
validate the constants to a measurable degree for the purpose in hand. 
We have felt it desirable to express in some manner the relative 
value of the electrical conductivity. 
While Chandler (9), Dixon, and Atkins (13) f and more recently Mason 
(45), have attempted to differentiate between electrolytes and non¬ 
electrolytes by expressing the conductivity in terms of the osmotic 
concentration which would be produced by a solution of a specific solute 
(KC 1 ) of the same electrical conductivity as the sap, it has seemed 
to us wisest to limit ourselves, as in earlier papers, to the purely numerical 
ratio of one constant to the other. We have, therefore, merely em¬ 
ployed the ratio of the specific electrical conductivity to the freezing 
point depression as a measure of the relative concentration of dissociated 
ions and total solutes (both dissociated and nondissociated electrolytes 
and nonelectrolytes). It is impossible to attach any specific chemical 
meaning to the ratio k/A. It is, however, useful for purposes of com¬ 
parison. 
The values of hydrogen-ion concentration have been calculated by 
the formula 
p -1 1 - E '~ E 
H 10g [H] 0.0001983 T* 
where E' is the electromotive force in millivolts of the tissue fluid under 
investigation as read from the voltmeter, E is the E. M. F. of the KC 1 
calomel electrode employed (taken as E = 0.2828 volt for the normal. 
KC 1 electrode), and T the absolute temperature. 8 
statistical analysis of data 
In the analysis of the series of measurements it has been necessary to 
employ to some extent the methods of the modem higher statistics. 
The simpler biometric notation is now familiar to most biologists. When 
special methods are used, formulas are given. 
PRESENTATION AND ANALYSIS OF DATA FOR THE COMPARISON OF 
PARENTAL TYPES 
Because of the large number of factors which might influence the 
results of physicochemical measurements on the tissue fluids of a crop 
plant such as cotton, and because of the fact that the varieties considered 
in 1920 and 1921 are not in all cases the same, it seems desirable to 
present the results of the preliminary investigation carried out by two 
of us in 1920, as well as the results of the more carefully planned in¬ 
vestigation of 1921. 
* We are deeply indebted to Mr. C. J. Xing, who encouraged us to monopolize practically the whole 
of his laboratot space while our work at Sacaton was in progress and facilitated our work in every way 
tn his power. 
