Nov. 20, 1916 
Size of Cannon Bone 
367 
Figure 4 shows a rise beginning at 19.5 cm., which indicates that 
matings of parents both under 11 years old have given gradually increas¬ 
ing percentages of the larger size classes. 
Table IV .—Average size of the cannon bone in the females in relation to the age of both 
parents 
Age of parents. 
Number of females having a camion bone of a 
given size (cm.). 
Average size of 
cfltmnn bone. 
18 
i8. s 
19 
19-5 
20 
20.5 
21 
Total. 
Both parents 10 years old and 
younger. 
Sire 10 years old and younger, 
the dams older than 10 
years. 
Sire older than 10 years, 
the dam 10 years old and 
younger.. 
Both parents older than 10 
years. 
Total.. 
40 
26 
t 
16 
8 
89 
53 
25 
16 
25 1 
144 
IOI 
50 
166 
98 
5 6 
27 
i6 5 
66 
48 
29 
43 
20 
7 
5 
25 
5 
3 
1 
779 
412 
256 
136 
Cm. 
19. 386^:0. 020 
19. 277 ±0. 021 
• 
19. 275±0. 026 
19. 291 ±0.036 
90 
*83 
546 
347 
308 
75 
34 
i>5 8 3 
Table V .—Averages of the deviations of the daughters from their dams t grouped according 
to the age of both parents 
Age of parents. 
Number of daughters having a given deviation in the size of 
the cannon bone (cm.). 
Average 
-2. 5 
— 2 
— 1. 5 
— 1 
—0. 5 
0 
0-5 
I 
i -5 
2 
2. t 
3 
3.5 
Total. 
deviation. 
Both parents io years old 
and younger. 
0 
4 
17 
66 
104. 5 
133 
98. 5 
97 * 5 
35 
10. s 
1 
0 
1 
S68 
Cm. 
0. i3i±o. 024 
The sire io years old and 
younger. The dams 
older than io years. 
0. 5 
5-5 
8-5 
24*5 
34 
60.5 
39 
29 
12.5 
2. s 
0. s 
1 
0 
218 
0. 046±o. 040 
The sire older than 10 
years. The dam io 
years old and younger.. 
Both parents older than 
10 years. 
1 
3 
7 
18. s 
38 
50 
38 
24 
5 
i *5 
0 
0 
0 
186 
—0. oi6±o. 039 
0 
2 
i -5 
4 
12. s 
17 
10.5 
7 
5*5 
0 
0 
0 
0 
60 
0. o67±o. 072 
To show how the measurements of the cannon bones of the offspring 
deviate from those of the parents the writer has tabulated (Table V) the 
deviations of the daughters from the dams—that is, when the measure¬ 
ment of the cannon bone of the dam is 20 cm. and the cannon bone of the 
daughter is 19 cm., the daughter is entered in Table V under — 1. In 
this table the mares that have both parents 10 years old and younger 
give an average deviation of 0.131 ±0.024 above the dam. This is 
times as large as the probable error. For the mares that have the sire 
10 years old and younger, the dam being older than 10 years, and the 
mares with both parents older than 10 years, the difference is practically 
the same as the probable error. For the mares whose sires are older 
than 10 years and the dam younger, the difference is slightly negative 
