370 
Journal of Agricultural Research 
Vol. XXIX, No. 8 
and about 30 days later for the cock¬ 
erels, or when they reach about 75 per 
cent of their mature weight. The 
second part of the curve for both 
male and female is a straight line, 
but not a horizontal line as in the 
following linear measurements.. This 
may be explained in part by the fact 
that this measurement is not entirely 
a skeletal measurement because it is 
affected by the distention of the abdo¬ 
men. The greater increase in body 
weight in the pullets after completion 
of ossification is in part due to the addi¬ 
tional weight of the reproductive tract 
and the greater amount of fat. Still 
these two factors will not account for 
all the difference. We must, therefore, 
conclude that the maximum length, or 
days, after which time it remains con¬ 
stant at 34.40 cm. The back-toe meas.- 
urements were also plotted; but the 
curve corresponded closely to that for 
the leg (except that it was about 1.5 
cm. greater) and it has, therefore, been 
omitted from the charts. The left 
leg and left wing only were measured. 
The growth in length of the leg corre¬ 
sponds closely with that of the body, 
the completion of growth (curves be¬ 
coming nearly horizontal) being at 
nearly the same time for each. The 
males become taller, however, and con¬ 
tinue to increase in height after the 
females have attained their maximum 
height. The growth of the length of 
the leg is practically completed at 141 
days in the males and at 106 days in 
Fig 4—The upper set of curves and individual cases show the length of the leg (in centimeters) from tho 
greater trochanter of the femur to the tip of the extended middle toe. The length of wing from the 
greater tuberosity of the humerus to the tip of extended wing is shown in the lower part of the chart 
the fusion of the epiphyses and dia- 
physes occurs earlier in the pullet, not 
only in relation to age but also in rela¬ 
tion to the attainment of the total 
body weight. 
Extremities. —Figure 4 shows the 
increase in length of the leg in the upper 
curves and of the wing in the lower 
curves. The formula from which the 
curves for leg length were drawn is: 
Y = X 0 - 75 —0.05X+6.68 
in which Y represents length of leg in 
centimeters and X represents age in 
days. For the males the formula 
applies from 5 to 141 days. The 
curve then remains constant at 40.5 
cm. The formula was used in draw¬ 
ing the curve for the females from the 
fifth to the one hundred and sixth 
the females. In this chart the average 
leg length for the mature males is 40.5 
cm. and 34.4 cm. for the mature fe¬ 
males. In all the charts of the linear 
measurements the “adults” are larger, 
but they were selected from their 
groups as heavier chickens and conse¬ 
quently would be apt to have a larger 
skeleton and be larger in other respects. 
The lower curve in Figure 4 shows 
for the wing length a less marked sex 
difference. The formula for the curves 
of wing length is: 
F = X°- 58 +0. 028X + 3.12 
in which Y represents length of wing 
in centimeters and X represents age 
in days. The formula was used for 
the males from 5 to 130 days, after 
which the curve remains constant at 
