376 
Journal of Agricultural Research 
Vol. XXIX, No. 8 
plotted against the gross body weight. 
No formula or curve was made for 
this chart because the individual cases 
shown on the chart are too variable. 
In the very young chicks the wattles 
were so small that they could not be 
separated from the integument over 
the mandible. As soon as they could 
be distinguished they were removed 
and weighed with the comb. When 
plotted against age or body weight, 
the comb and wattles of the male 
birds appear more irregular in their 
growth than those of the females. The 
ear lobes were not weighed in all cases 
and hence are not shown for all the 
The muscles and integument form 
nearly straight lines when thus plotted, 
as shown in Figures 8 and 11. The 
musculature was also plotted on age, 
and the resulting curve resembled the 
curve of gross body weight (fig. 1). 
Figure 11 shows possibly a very slight 
sex difference in the heavier chickens, 
but only the one curve and formula 
are given. The percentage weights of 
the muscles show an increase from 
about 21 or 22 per cent of the net 
body weight at hatching to a little 
over 50 per cent for some of the larger 
chickens. The musculature of the 
three older cockerels averages about 
Fig. 11.—Weight of the muscles in gm. as the heavier line. The lighter and more sharply curved 
line represents the percentage weights of the musculature. Both are plotted on gross body weight 
chickens. Their increase in weight 
appears to be more regular than that 
of the comb and wattles. 
MUSCULAR SYSTEM 
The absolute weight of the skeletal 
musculature and also its percentage 
weight, plotted against gross body 
weight, are shown in Figure 11. The 
formula for this chart is: 
F=(0.01Z) 1 * 8 + 0.35X-5 
from 50-2,600 gm. gross body weight. 
Y represents the weight of the mus¬ 
culature in grams and X represents 
the gross body weight in grams. 
50 per cent while that of the three 
hens averages only about 43 per cent. 
There is a similar difference in the 
older chickens in this series, the muscles 
of the males forming a larger percent¬ 
age of the net body weight than do 
those of the females. It is popularly 
supposed that there is relatively more 
“meat” (muscle) in a hen than in a 
rooster, but the present data show 
that this is incorrect. 
The musculature in the chicken at 
first increases in weight more rapidly 
than the rest of the body and later 
forms about 50 per cent of the net 
body weight, with no marked sex 
