Feb. 2, 1924 
Tissue Fluids in Cotton 
271 
seed came from isolated cultures of naturally pollinated (not selfed) 
plants. Mr. G. S. Meloy, who furnished the seed, considers it pure as 
far as varietal characters are concerned. It is not, however, as closely 
inbred as is the “Pima selfed” of the experiment. 
The “Pima bulk” of the experiment was grown from seed from a 
selected but not strictly inbred strain. While unquestionably pure Pima, 
it was not of controlled, self-fertilized, ancestry. 
The Meade bulk and the Acala 4 bulk used in the planting were both 
from lots of seed sent to Sacaton by Mr. Meloy in 1919 and held over 
until 1921. Both are supposed to be varietally pure, although not 
resulting from controlled inbreeding. 
The F t hybrid was derived as follows: The Pima parent of the PxM F t 
used was a plant representing the sixth inbred generation in progeny 
Pima H1-2 A of 1920, a sister progeny of PH 1-5 Acala A which furnished 
the ‘ ‘ Pima selfed ’ ’ seed in the experiment. 
The Meade parent of the P X M F x was a plant grown at Sacaton in 1920 
from seed obtained from the experimental plantings in Georgia. This 
plant was one of a lot grown from seed produced by naturally pollinated 
(not selfed) dowers in an isolated planting of this variety in Georgia, and 
was considered “pure” by Mr. Meloy, who sent it to Sacaton. 
Flowers were selfed on a few individuals in the 1920 planting at Saca¬ 
ton, and these furnished the “Meade selfed” seed planted in the physico¬ 
chemical experiments of 1921. Thus the Meade parent of this hybrid 
was by no means so closely bred as the Pima parent. 
It may be noted that the seed used was not of exactly the same age 
for all of the cultures. This difference in age probably does not influ¬ 
ence the physiological characteristics of the plants in any way, since the 
cotton seed is very long lived. 5 
The F t hybrids between Egyptian and Upland cotton show intensi¬ 
fication in most size characters. In respect to other characters the hybrid 
mean may be intermediate or may approximate that of one or the other 
parent. The Fj is highly uniform. The greater vegetative vigor is 
conspicuously shown by the accompanying plate (PI. 1), in which the 
F x hybrid is shown between the Egyptian and the Upland parental 
types. 
CULTURAL METHODS 
In preparing the planting scheme it seemed desirable to grow the plants 
under the standard conditions of the Cooperative Testing Station experi¬ 
ments with the cottons. This involved the use of an irrigation border 
26.5 feet in width by 400 feet in length. This accommodated seven 
rows of cotton 3.5 feet apart, with plants 1 foot apart in the rows. In 
order to avoid the influence of soil heterogeneity, which has been shown 
to be an important factor in crop yields (21, 32), and which may reason¬ 
ably be assumed to be an important factor in determining the physico¬ 
chemical properties of the tissue fluids of the plant organism in regions 
4 Acala is an Upland variety of Mexican origin, introduced by G. N. Collins and C. B. Doyle, and adapted 
by selection to conditions in the United States by O. F. Cook and his colleagues. Acala is a big-boiled 
type, producing fiber from i -h to inches long. 
5 It has been found that Pima seed which had been stored at Sacaton during nine years germinated readily 
when planted. Moreover, the stock of Pima planting seed distributed to farmers in the Salt River Valley 
in the spring of 1921 had been held over one year at Tempe. In order to make sure that its viability was 
unimpaired, the germination was thoroughly tested by the seed laboratory of the Bureau of Plant Industry 
just before the seed was distributed, and the average germination percentage proved to be exactly the same 
as that for the same stock of seed shortly after it was harvested. The seed was approximately one year 
older when the second series of germination tests were made. There is a possibility that seed of the Upland 
cottons may lose its viability more rapidly, but this is improbable. 
