Oct. 15, 1924 
Postnatal Growth of the Single-Comb White Leghorn 391 
than is indicated in the change in 
weight as shown in Figure 27, for the 
diameter of the largest ovum increases 
slowly while at the same time there is 
almost no increase in the weight of the 
ovary. The first noticeable increase 
in size of the ova was on the free or 
ventral surface of the ovary. No 
measurements were made to verify 
this observation, for only the largest 
ovum was measured for each ovarv. 
(See Table II.) 
In every female but one (the three- 
day chick) only the left ovary was 
found, and no trace of the right ovary 
was seen. As stated above, the supra¬ 
renal on the left side is more and more 
.enveloped by the ovarian ligament as 
found in the growth of the mammalian 
testes. There is (1) a period of slow 
growth up to 400 gm. in body weight 
(or about 50 days); then (2) an in¬ 
crease in growth from 400 to 700 or 
800 gm. in body weight (50-80 days); 
and then (3) a period of rapid or 
puberal growth from 1,800 to 1,950 
gm. in body weight (210-260 days); 
and (4) a terminal plateau or period 
following sexual maturity. (This last 
period does not show well in the accom¬ 
panying chart.) 
Autopsy of the males showed an 
apparent difference in the size of the 
two testes, consequently the right and 
left testes of each male bird (with 
three exceptions) were weighed separ- 
Fig. 28.—Weights of the Testes (in grams), shown as solid dots,plotted on gross body weight. The five 
cases in which the weight of the Testes exceeds 20 gm. are shown at the upper margin of the chart, and 
the proper weights indicated. No curves were made, since the cases are too irregularly arranged 
the ovary increases in size, but on the 
right side the suprarenal is covered by 
only a thin capsule of connective tissue. 
In the three-day chick there was a 
small mass of tissue (not weighed) 
ventral to the right suprarenal which 
looked as though it might be a degen¬ 
erating ovary. Unfortunately, it was 
not preserved for histological study. 
Testes. —The growth in weight of the 
testes (without epididymis) plotted 
against gross body weight is shown in 
Figure 28. Here also no attempt has 
been made to derive a formula or 
draw a curve, for the cases are too few 
in number and too irregularly distrib¬ 
uted. There are, however, definite 
indications of the four-phase curve 
ately and the sum of the two testes 
plotted in Figure 28. Up to 179 days 
the left testis is usually heavier. In 
29 specimens under 179 days old the 
left testis was heavier, and in 4 the 
right was heavier. Beginning with 
the one hundred and seventy-ninth 
day the right testis was heavier in 9 
birds and heavier on the left in 4 speci¬ 
mens. Up to 179 days the sum of the 
weights of the right testes of all speci¬ 
mens was 84.7 per cent of the sum of 
the weights of the left testes. From 
the one hundred and seventy-ninth 
day the sum of the weights of the left 
testes in all specimens was 91.3 per 
cent of the sum of the weights of the 
right testes. The seven males in the in- 
