434 
Miscellanea 
The chief constants measuring the variability in the fecundity of these two breeds for the 
year 1902 are given in Table I. 
TABLE I. 
Constants for Variation of Fecundity in Brood Sows. 
Constant 
Poland China 
Duroc Jersey 
Mean 
Standard Deviation 
Coefficient of Variation ... 
7 -435+ -010 
2-038+ -013 
27-411 + -172 
9-337+ -021 
2-427+ -016 
25-997+ -169 
The first thing noted here is the large difference in the values of the means. This, as Rommel 
has pointed out, confirms the common observation that Duroc Jersey sows are more prolific than 
the Poland China. The difference of almost two pigs is very marked. In the constants measuring 
the variability of the two breeds only a small difference is found. The standard deviation is 
slightly larger in the Duroc Jersey. When considered with reference to the mean, however, it is 
seen that the coefficient of variation is larger in the Poland China by nearly 1-5 per cent. This 
when taken in connection with its probable error, which for the difference of these two quantities 
is +0-241, is to be regarded as certainly significant. 
Considering the coefficient of variation with reference to fecundity in other animals we find 
that this value is somewhat lower than the average. Fecundity like many other physiological 
characters appears to have a high coefficient of variability. Powys* finds that for man the 
number of children exhibits a coefficient of more than 48%. For the horse Pearson t finds a 
value slightly less than 25°/^. For mice the data given by Weldon| lead to a coefficient of 
variation of 37-5 In the case of ovulation of the domestic hen§ the coefficient of variation 
averages 34-2 
Table II gives the analytical constants which exhibit the further characteristics of these 
distributions. The material was not grouped, nor were Sheppard's corrections used. The unit 
for the moments is one pig. 
It may first be noted that for the skewness shown by these distributions we have the values 
of +0-05 and +0-07. The probable error for each is +0-01. Thus there is a small but significant 
positive skewness. The Potand China with the smaller mean and larger variability shows a 
slightly larger skewness. However, the difference is so slight that it cannot be regarded as very 
important. Comparing the skewness of these distributions with fecundity and fertility curves 
for other organisms, we find that it is of about the same magnitude as that given by Powys for 
man, viz. +0-08||. Schuster**, however, gives data for the size of human families with one or 
more congenitally deaf persons, which lead to a skewness of about +0-43. For fecundity of 
mares Pearson gives a value of nearly —0-13. In the domestic hen the skewness has an average 
value of -0-21. 
* Biometrika, Vol. iv. p. 251, 1905. [Various values from 47 to 70 are deducible from Pearson and 
Lee's data, P)dl. Trans. 1899, Vol. 192, A, pp. 280—90.] 
+ Biometrika, Vol. i. pp. 289 — 292, 1902. Only the moments are given here. 
+ Biometrika, Vol. v. p. 442, 1907. 
§ Pearl, E. and Surface, F. M. In a bulletin of the Bureau of Animal Industry, U. S. Department 
of Agriculture, Washington, D.C., now in press. 
II [There appears to be a slip here. Powys' only comparable data occur Biometrika, Vol. iv. p. 251 
and give skewness = -38, and this does not wholly exclude the sterile cases as in the sow data. Ed.] 
** Biometrika, Vol. iv. 1906, p. 474. [Pearson's data give Anglo-Saxons -56, Danes "42, Chances of 
Death, Vol. i. pp. 75—88, 1897.] 
