Oct. 15,1924 Postnatal Growth of the Single-Comb White Leghorn 
379 
18.5 (for the sixth day, the highest of 
all), 15 and 14. 
Welcker and Brandt '{28) give 5.02 
per cent as the average for the canal 
in their two male chickens (adult). 
This is very close to that of the older 
Minnesota cockerels and but slightly 
higher than that of the hens. Jack- 
son (8) gives about the same percent¬ 
age values for the adult rat (esophagus 
not included), but finds that it in¬ 
creases from an average of about 2.4 
per cent in the newborn to a maximum 
of about 8 per cent at six weeks of 
age. Thus the maximum relative 
weight of the digestive tube is attained 
much earlier in the chick and at this 
time it forms twice the relative weight 
of the tube in the rat. The greater 
weight of the tract in the chick at the 
beginning may be correlated with the 
The cases appear more irregularly 
scattered than in the charts of the 
other parts of the digestive tube, for 
perhaps three reasons: (1) The scale of 
the ordinates is larger; (2) the separa¬ 
tion of the stomach from the rest of the 
digestive tube was rather difficult, for 
there is no sharp line of separation 
between it and the esophagus; (3) the 
proventriculus may vary in size more 
than the other parts. The curves of 
both absolute and relative weights are 
very similar to the curves for the 
entire digestive tube (fig. 13). 
Gizzard. —Figure 15 shows the ab¬ 
solute weights of the gizzard, separately 
plotted against gross body weight. 
The lighter line shows the percentage 
weights. The formulas are: 
F = X°- 48 +0.01X-5.12 
Fig. 14.—Growth of the stomach or proventriculus (without contents), plotted on gross body weight 
difference in diet. In addition the 
chicken has the heavy-walled gizzard 
which frequently equals the weight^of 
the intestines, crop, and esophagus 
together. 
Stomach.— Figure 14 shows the 
growth in the absolute and relative 
weight of the stomach or proven¬ 
triculus, plotted against gross body 
weight. The formulas are: 
Y=X°‘ Z - 0.0002X - 2.96 
from 80-1,200 gm. gross body weight, 
Y =0.00042 {X- 1,200) +5.19 
from 1,200-2,500 gm. gross body 
weight. 
Y represents the weight in grams of 
the stomach and X represents the 
gross body weight in grams. 
from 80-1,500 gm. gross body weight, 
7=0.0062 (X- 1,500) + 43.33 
from 1,500-2,500 gm. gross body 
weight. 
Y represent^ the weight of the 
gizzard in grams and X, the gross body 
weight in grams. 
The relations are discussed in the 
following paragraph. 
Intestines. —Figure 16 shows the ab¬ 
solute and relative weights of the intes¬ 
tines (also including crop and esophagus) 
plotted against the gross body weight. 
The formulas are: 
Y = (X+100)°* 57 — 0.002X —14.57 
from 30-1,200 gm. gross body weight, 
7=0.0057 (X-l,200) +42.59 
from 1,200-2,500 gm. gross body 
weight. 
