366 
Journal o f Agricultural Research 
Vol. XXIX, No. 8 
The technic of the autopsy was as 
follows: The chickens were chloro¬ 
formed and then weighed. The feath¬ 
ers were pulled off and the chicken 
again weighed, the difference giving the 
weight of the feathers. The measure¬ 
ments of the chick were made after the 
removal of the feathers and the second 
weighing. The bird was laid right 
side down on a piece of paper, the 
neck gently straightened and the 
length from the tip of bill to anus 
marked on the paper. The distance 
from back to toe was measured in a 
similar manner. The other measure¬ 
ments were made with a pair of dividers. 
They include the following: Length of 
left leg from tip of toe to greater 
trochanter; length of left wing, from 
tip to proximal end of humerus; 
length of head; dorso ventral and 
transverse diameters of the thorax, just 
behind the anterior end of the sternal 
crest. 
The head was then cut off, the 
incision being made close to the base of 
the skull and through the spinal cord 
as it passes through the foramen 
magnum. The esophagus and trachea 
were severed just below the pharynx. 
The blood was allowed to drain from 
the severed vessels and was not meas¬ 
ured. The blood, larger masses of fat, 
mesenteries and larger vessels and 
nerves were not weighed separately. 
The integument was next removed. 
This includes the skin, with scaly skin 
from legs and feet, horny beak and 
claws; also some dermal fat which 
could not easily be removed, and the 
dermal muscles, especially in the neck 
and lateral thoracic regions. The 
uropygial glands w~ere removed with 
the skin. The wattles and ear lobes 
were not weighed separately at first, 
and so are included in the integument 
of the smaller chicks. They were not of 
sufficient size to modify the results, for 
as soon as it was possible to separate 
them they were weighed separately. 
So far as possible, all fat and mesen¬ 
teries were removed from the viscera, 
and they and the parts of the body 
were immediately put in a moist cham¬ 
ber until weighed. The organs were 
weighed in closed containers on a 
chemical balance sensitive to one-tenth 
of a milligram. The body, after re¬ 
moval of all viscera, was cleared of all 
excess fat, mesenteries, etc., and 
weighed, in the case of the larger 
chickens, on a laboratory balance sen¬ 
sitive to one-tenth of a gram. 
The digestive tube includes all of the 
canal from beginning of esophagus to 
termination of intestine in the cloaca. 
The cloaca was not included. The en¬ 
tire digestive tube, together with con¬ 
tents, was first weighed; then the stom¬ 
ach and gizzard were cut out, opened, 
and each weighed after removal of 
contents. The crop was opened and 
contents removed. Next by gentle 
pressure the contents of esophagus and 
intestines were forced out. Then 
esophagus, crop, and intestines were 
weighed together. From these weigh¬ 
ings the weight of the entire empty 
canal and the “tare”, weight of con¬ 
tents, were computed. 
The muscles were then removed by 
careful dissection, and the ligamentous 
skeleton, wdth contained central 
nervous system, was weighed. Then 
the brain and the spinal cord were re¬ 
moved and weighed. 
The data were recorded upon in¬ 
dividual record cards and finally 
plotted in the form of the various 
graphs and curves shown in Figures 1 
to 31, inclusive. 
The curves shown in Figure 1 are 
point-to-point curves made by connect¬ 
ing the average body weight of the chick¬ 
ens for each week. In the construc¬ 
tion of the other curves the numerical 
averages of the gross body weight and 
the absolute weight of the organ were 
determined in general for each in¬ 
crease of 200 grams in gross body 
weight, and these average points were 
plotted on the preliminary chart. Then 
by means of French curves the growth 
curves were drawn in to fit the group 
averages as closely as possible. Later 
an empirical formula was determined 
for each curve and the curves as shown 
on the final charts were drawn accord¬ 
ing to the formulas. The final charts 
show the weights or measurements of 
the individual chickens as dots and 
circles and the growth formula em¬ 
pirically determined is shown by the 
heavier line. The percentage weights 
were plotted on the same abscissae as 
the absolute weights of the same organ. 
Double-weighted medians were deter¬ 
mined for. these values as for the 
weights in grams, as described above. 
Then by means of French curves a 
curve was drawn through the double- 
weighted medians. This curve, with¬ 
out individual percentage values, is 
shown as the lighter line on the final 
charts. The net body weight (gross 
body weight minus the weight of the 
contents of the digestive tube) was 
used in determining the percentage 
weights. Crelle’s Rechentafeln was 
used in computing the data. 
