138 Variation and Inheritance in Ai^his 
TABLE V. 
Dimension 
Mothers (60) 
weighted witli their 
fertility 
Cliildren (368) 
Grandmothers (30) 
weighted with their 
fertility 
Grandchildren (291) 
S. D. 
Coefficient 
of 
Variation 
S. D. 
Coefficient 
of 
Variation 
S. D. 
Coefficient 
of 
Variation 
S. D. 
Coefficient 
of 
Variation 
Frontal Breadth {AB) 
Unit = "01 mm. 
2-7682 
7-3533 
2-9647 
8-2587 
2-2815 
6-0739 
1-9099 
5-6283 
Length of R. Antenna 
Unit ='01 mm. 
9-2262 
10-8205 
10-9367 
12-9682 
7-3593 
8-7707 
7-9972 
10-4422 
CD 
Eatio-r^x 10 
AB 
1-4974 
6-6054 
1-8363 
7-8244 
1-2735 
5-6692 
1-6309 
7-2270 
We must compare the variability of the third generation (eighth and ninth 
columns) with the variability of the grandparents (sixth and seventh columns), the 
fewness of which render the values somewhat aberrant. The diminished vai'iability 
of the frontal breadth (5 6283) of the third generation must be referi-ed to the 
direct action the environment, for we have already seen that the external 
conditions have an important influence on the ultimate size attained by the 
mature offspring, and apparently the standard deviation is also reduced in the 
case of our criterion of size, the frontal breadth. 
It is interesting to notice that here as in man* the variability of children is 
greater than that of parents, the adult children being a population only partially 
selected. Similarly the variability of the grandchildren is greater than that 
of their grandparents (with the exception of the frontal breadth mentioned above). 
Also the variability of the grandmothers is considerably less than that of the 
mothers, for the grandmothers are a doubly selected population, being in fact only 
those individuals which are capable of ^YoAwcmg fertile offspring. 
These results prove that the variability of the race, measured by the coefficient 
of variation, is by no means smaller than among sexually reproduced foims. This 
coefficient varies considerably for different characters ; to mention a few examples 
the following may be cited. Prof Pearson and others have shown that for 
stature in manf the coefficient of variation varies from about 3 — 4, for the 
length of the long bones | from 4 — 6. Breadth of wing of 98 wild ^ Strenia 
clathrata^ had a coefficient of 4-57. 
* Phil. Trans. Roy. Soc. Vol. 187 (1896) a, p. 270. 
i Ibid. p. 278. 
+ Lee and Pearson, R. S. Proc. 1897, Vol. 61, p. 348. Warren, Phil. Trans, of the Roy. Soc. 1898, 
Vol. 189, B, p. 140. 
§ Not yet published. 
