FLOWEKS AND BOLLS OF PIMA AND ACALA COTTON 25 
a boll was present at the first node the period at node 2 was 65.454 ± 
0.791 days, a difference of 3.676 ±1.108 days, which shows the 
increased period as significant. On node 1, bolls of the same date as 
those on node 2 required a mean period of 62.076 ±0.462 days to 
mature, giving evidence that bolls on the second nodes, when not 
preceded by a boll on node 1, developed in approximately the same 
length of time as for bolls at the first node. 
PRACTICAL APPLICATION OF THE DATA TO COTTON GROWING 
The facts shown by the preceding data have applications in cotton 
growing. The efficiency in the maturing of bolls is greatest on the 
inner or basal nodes of the fruiting branches and is greatly lessened 
on the outer nodes. The greater efficiency of the branches of the 
main stalks in this regard over those of the vegetative limbs is 
indicated. Plants without vegetative limbs and with short fruiting 
branches shed a smaller proportion of squares and develop a greater 
proportion of squares into mature bolls than do larger plants which 
have long fruiting branches and vegetative limbs. 
A method of close spacing cotton plants, called the " single-stalk' ' 
method, by which the development of vegetative limbs is very greatly 
restricted and which places rather definite limits on the length of the 
fruiting branches, has been described in several publications (5, 6, 
7, 8, 20). This method of growing cotton was evolved to take 
advantage of the facts above recognized and has usually resulted in 
earlier and larger yields than by following the old method of leaving 
the plants far apart in the rows, when long fruiting branches and 
many vegetative limbs are produced. 
With relation to cotton growing under boll-weevil conditions, data 
such as shown in this bulletin may be of special value in answering 
questions pertaining to the rapidity of square and boll development 
and to when these features of growth begin and the length of the 
periods in which they are active. Also in testing or comparing 
varieties of cotton the accumulation of similar data will allow a more 
complete analysis to be made of the various phases of fruit develop- 
ment than has been practicable in the past. 
SUMMARY 
In making a comparison of Pima Egyptian with Acala cotton at 
the United States Field Station, Sacaton, Ariz., in 1924 and 1925, 
data were obtained on several features of plant behavior in relation 
to fruit production. Records of phases of square and boll develop- 
ment were made throughout both seasons on 20 plants of each 
variety by methods that made it possible to compare not only the 
two varieties but the different parts of the plants and different periods 
of the growing season. 
More floral buds or " squares" were produced by the Acala plants 
in each season than by the Pima plants. The shedding of buds in 
1924 amounted to 37 per cent on Pima and 36 per cent on the main 
stalks of Acala but was 55 per cent on the vegetative limbs of the 
latter, square shedding from complete Acala plants amounting to 
40 per cent. 
Squares shed from the main stalks of Pima and Acala in 1925 
amounted to 44 and 47 per cent, respectively; those shed from vegeta- 
tive limbs amounted to 72.5 and 63 per cent, respectively; and the 
