330 
family, the ‘mode,’ is between two and three; 
the median family is about 3} and the mean 
family one larger. The median fertility is, 
however, about 54, and it follows from this that 
the most fertile quarter of the parents produce 
one half of the next generation. The same 
general relations hold for the extensive statis- 
tics of Copenhagen families collected by Rubin 
and Westergaard, but the fertility is greater. In 
both cases there is a deficiency, according to 
the theoretical distribution, of families of five 
and six children, due probably, as Mr. Pearson 
holds, to voluntary control. I cannot, however, 
agree with him that the curve shows that con- 
trol is not exercised in the case of families of 
other sizes, or that in the case of no children it 
is excessive. In the latter case there are special 
anatomical and physiological causes producing 
sterility, which would not be factors in the 
amount of fertility. 
Mr. Pearson finds that there is a selective 
death-rate increasing with increased fertility, 
but it would only slightly check ‘reproductive 
selection,’ and he concludes that in the case of 
civilized man natural selection at present ap- 
pears to be quite secondary to reproductive 
selection as a factor of progressive evolution. 
An extreme Neo-Darwinian might, indeed, find 
it difficult to tell us why families do not in- 
crease indefinitely in size, or why infant mor- 
tality does not eliminate itself. We must be- 
lieve that deviations from the mean are not 
always stable hereditarily and are in definite 
directions. The degree to which individual 
fertility is a stable variation can only be deter- 
mined by statistics not yet collected. It is, 
however, clear that race or class fertility, 
whether due to physiological or psychological 
causes, will in a comparatively short time pro- 
duce great changes in every race and in the 
survival of races. Thus the Bretons are sup- 
planting other French stocks, and our New 
England stock is in danger of extermination. 
The essay on ‘ Variation in Man and Woman’ 
occupies one-third of the first volume. As the 
result of some 155 cases of variation for both 
sexes, covering a wide field, Mr. Pearson finds 
that woman is, relatively to size, not less, but 
probably slightly more, variable than man. 
This is contrary to the common opinion, but 
SCIENCE. 
(N.S. Vou. VI. No. 139. 
had been proved previously by Mr. Galton for 
sensation-areas. The variation in brain-weight 
is of special interest, but the data are so con- 
flicting that they are not of great value ; the 
coefficient of variation is, however, sensibly 
the same for the two sexes. Mr. Pearson criti- 
cises somewhat bitterly those who have as- 
sumed, on insufficient evidence, the greater 
variability of the male and drawn therefrom 
sociological conclusions. I think, however, 
that the experience of those who have taught 
both mén and women will favor the greater in- 
tellectual variability of the male. The colla- 
tion of examination papers marked without 
reference to these matters would be of interest. 
Supposing the male to be more variable in in- 
tellect and character, as seems sufficiently evi- 
dent from the history of civilization, it would 
still remain undecided whether this were due 
to ‘nature’ or ‘nurture,’ and sociological in- 
ferences can only be drawn with caution. 
This volume contains three essays criticis- 
ing, respectively, Mr. Kidd’s ‘ Social Evolution,’ 
Lord Salisbury’s ‘ President’s Address’ before 
the British Association and Mr. Balfour’s 
‘Foundations of Belief.’ Mr. Pearson has rather 
an easy task. Mr. Kidd’s book received abun- 
dant attention and was lauded by Mr. Wallace 
in Nature, but it is already half forgotten. Mr, 
Pearson’s arguments for the comparative unim- 
portance of intra-group selection for human 
progress are, however, deserving of considers 
ation. Most men of science will agree with 
Mr. Pearson’s arraignment of Lord Salisbury 
and Mr. Balfour. It is a particularly futile 
form of argument to pass from zgnoramus to 
ignorabimimus and thence to credendum est. Mr. 
Pearson holds that the comparative orthodoxy 
of the Conservative leaders was of much ad- 
vantage to them in the last elections. The 
writing of books on science and philosophy is, 
however, a kind of demagogy of which we 
should be glad to see some trace in America. 
Mr. Pearson is undoubtedly correct in stating 
that thoughtful men of science do not hold the 
materialistic views attributed to them by Mr. 
Balfour, but Iam not sure that his own ideal- 
ism helps greatly in treating the problems of 
physical science. When it is said that in 
science we are concerned not with phenomena, 
