3 68 
Journal of Agricultural Research 
Vol. VII, No. 8 
72 
It is noteworthy that the daughters deviate from the dams by a signifi¬ 
cant amount only when both parents are io years old and younger, and 
in this case the daughters are larger than the dams in cannon-bone cir¬ 
cumference. Figure 5 shows the percentages of mares in the various 
classes with both parents 10 years of age and younger. The curve was 
constructed from Table V. The offspring of parents under 11 years of 
age constitute about 55 per cent of the total number of individuals en¬ 
tered in the table, but the curve shows that the percentage of the daugh¬ 
ters which average higher than their dams is greater than 55 per cent 
when both parents are 
under 11 years of age. 
It takes large num¬ 
bers to establish the 
significance of the dif¬ 
ferences with which we 
are concerned in this 
paper, and it is to be 
hoped that further 
data will be obtained 
in order to test this 
matter for other heavy 
breeds. However, the 
present study points to 
the following conclu¬ 
sions : 
(1) The age of the 
parent has an influence 
on the circumference 
of the cannon bone of 
the offspring. 
(2) Immature par¬ 
ents 2 to 4 years old 
give offspring with the 
the cannon bone as parents as old as 5 to 7 
2C/r. 
Fig, 5. —The percentages of mares in various classes deviating from 
their dams when both parents were under n years old. 
same measurement of 
years. 
(3) Parents older than 10 years considered as a class give offspring 
with lighter cannon bones than parents 10 years old and younger. In the 
breed examined there was found a larger percentage of individuals over 
average size whose parents were 10 years old or younger. On the other 
hand, the average individuals and those smaller have parents which are 
just as frequently under 10 years old as they are over. In other words, 
the lighter classes of cannon bone come as frequently from young as from 
old parents, but the heavier classes seem to come more frequently from 
younger parents. 
