36 
Journal o f Agricultural Research 
Vol. XXIX, No. 1 
A 2-centimeter cylindrical bob was 
used, suspended by a No. 30 wire. 
The viscosity was determined at once 
and after the addition of 0.2, 0.4, 0.6, 
0.8, 1.0, 1.2, 1.4, and 1.6 cc. of normal 
lactic acid. 
One hundred and twelve samples 
were studied, including 50 varieties of 
wheat representing the five commercial 
classes, Hard Red Spring, Durum, 
Hard Red Winter, Soft Red Winter, 
and White, obtained from 11 agricul¬ 
tural experiments stations in 10 West¬ 
ern States. The wheat samples had 
been milled and baked previously in 
the Milling Investigations Laboratory 
of the Grain Division of the Bureau of 
Agricultural Economics, United States 
— 0.060 =b 0.063 and not important or 
significant. These experiments, there¬ 
fore, confirmed the conclusions of pre¬ 
vious studies that the viscosity deter¬ 
minations indicated strength of gluten, 
although there was also a fairly good 
correlation between viscosity and crude- 
protein content. 
This preliminary study led to a trial 
of the viscosity test for determining 
the quality of promising F 4 selections 
in the present hybrid study. The lim¬ 
ited amount of grain produced from a 
plant selection prevents the making of 
a baking test. Seventy-five grams of 
wheat of each of 30 F 4 selections were 
milled as uniformly as possible and 
produced approximately 35 grams of 
straight flour. Because of the 
small amount of grain, uniform 
milling was very difficult and 
the results were not entirely 
satisfactory. The flour obtained 
was tested for viscosity, crude 
protein, gasoline color, and ash. 
The viscosity trials were con¬ 
ducted by the writer by the 
method decribed above. Flour 
from the Kota and Hard Fe¬ 
deration parent varieties, as 
well as Marquis, grown in 
check rows, were tested in 
duplicate in a similar manner. 
The viscosities obtained with 
these varieties, with increasing 
amounts of lactic acid until 
maximum viscosity was 
reached, are shown in Figure 
9. The distribution of the 
maximum viscosity of each of 
the 30 hybrid strains is indi¬ 
cated by dots in the Figure. 
The segregation by 20-degree 
freouenev classes also is shown 
in Table XXVII. 
The data show a wide seg- 
gregation with most of the 
hybrids intermediate between 
the parents, although one 
exceeded Kota and five were lower than 
Hard Federation. The average maxi¬ 
mum viscosity for the 30 hybrids was 
170 degrees MacMichael, compared 
with averages of 220, 203, and 129 
degrees MacMichael, respectively, for 
duplicate samples of Kota, Marquis, 
and Hard Federation. The disparity 
in numbers prevents any conclusion 
regarding the mode of inheritance of 
strength of flour, but there is distinct 
evidence of segregation and the vis¬ 
cosity test furnishes a promising 
method of attack by which to breed 
wheat for gluten quality. 
Fig. 9.—Viscosity curves for the Kota, Marquis, and Hard Fede¬ 
ration varieties, and maximum viscosity for 30 F 4 KotaX Hard 
Federation selections grown at Mandan, N. Dak., in 1923 
Department of Agriculture, at Wash¬ 
ington, D. C. 
The viscosity as determined by con¬ 
stant readings, in degrees MacMichael, 
was correlated with loaf volume, in 
cubic centimeters, and the important 
and significant positive correlation 
0.368 ±0.055 obtained. The viscosity 
of the same samples correlated with 
crude-protein content of the wheat 
(NX 5.7, 13.5 per cent moisture) 
gave a less important correlation of 
0.287±0.058. The correlation be¬ 
tween crude protein and loaf volume 
for the same 112 samples was negative, 
