Nov. 20, 1916 
Size of Cannon Bone 
365 
our other results may be a chance fluctuation. In fact, the apparent 
lack of harmony of this case with the others is largely due to the size 
of the cannon bone of one mare—21 cm. This mare was sired when 
the stallion, Kongen, was 12 
73 
7* 
70 
<o 
S3 
so 
4S 
S3 
1 
i 
7 ^ 
/ 
/ 
/I 
/ 
/ 
\ 
/ 
\ 
/ 
\ 
/ 
/3 /3-S /S> /3.S3Q 2073/CM- 
Fig. 2.—The percentages of mares with various-sized cannon 
bones, sired by io selected stallions when these were under 
11 years old. 
years old. The mother was 
6 years old. With all 10 
stallions it is remarkable how 
few there are of the daughters 
with a circumference of 20.5 
and 21 cm. in that class 
which was sired when the 
stallions were older than 
10 years. Taking the two 
classes as a whole, the writer 
finds for all daughters sired 
when the stallions were 10 
years old and younger at 
time of service that the aver¬ 
age cannon bone is 19.448 ± 
0.026 and for the other class 
the average is 19.232 ±0.027. 
The difference, 0.216 ±0.037, 
is significant, f or thedifference 
is nearly 6 times the proba¬ 
ble error. Figure 2 shows the percentage of the daughters of the 10 
stallions that correspond to different sizes of cannon bone when the 
stallions were 10 years and younger at the time of service. Just as in 
the case of figure 1, there is 
a perceptible rise, the curve 
beginning at 19.5 cm. In 
other words, gradually in¬ 
creasing percentages of the 
larger mares (those over 
19.5 cm.) were sired by these 
stallions when 10 years old 
or younger. 
The correlation between 
the age of the dams and the 
size of the cannon bone of 
their female offspring was cal¬ 
culated to ascertain whether 
a similar relationship held as in the case of the sires in Table I. Curiously 
enough, the coefficient ( — 0.062 ±0.017) is practically the same as that 
given in Table I. The total number of variates is not as large as that 
given in Table I, for the age of the dam is not as frequently registered 
Z3 /3S /sP ZS.S 30 30.S 3/CM 
Fig. 3.—The percentages of mares of various-sized camion 
bones bred from dams under 11 years old. 
