REVIEWS OF RECENT LITERATURE. 
GENERAL BIOLOGY. 
Fertility Inherited.— The sixth of Pearson’s famous “ Mathemat- 
ical Contributions to the Theory of Evolution,” published in the Zravs- 
actions of the Royal Society, has just appeared. It contains three 
parts, to which Professor Pearson, Alice Lee, and Leslie Bramley- 
Moore have contributed. The introductory paragraph reads: “I 
understand by a factor of evolution any source of progressive change 
in the constants — mean values, variabilities, correlations — which 
suffice to define an organ or character, or the interrelations of a 
group of organs or characters, at any stage in any form of life. To 
demonstrate the existence of such a factor we require to show more 
than the plausibility of its effectiveness; we need that a numerical 
measure of the changes in the organic constants shall be obtained 
from actual statistical data. 
As a result of numerical studies on fertility and fecundity! in man 
and the thorough-bred race horse, Pearson concludes: Both fertility 
and fecundity are inherited, and probably in the manner prescribed 
by Galton’s Law of Ancestral Heredity. 
Among the other valuable results are methods of finding the 
coefficient of correlation between brethren and between uncles and 
nephews, calculating from the means of the “relatives ” or “arrays.” 
The importance of the demonstration of the inheritance of fertility 
lies in the fact that the most fertile class tends to form a larger and 
larger percentage of the whole population. Now fertility is correlated 
with various physical qualities ; consequently, these physical quali- 
ties are bound to become predominant, if there is no interfering 
factor at work. 
Energy of Living Protoplasm.?— In this thoughtful work the 
famous pupil of Nageli has carried the science of the chemistry of 
1 Fertility is defined as the total number of actual offspring, while fecundity is 
the ratio of this last number to the maximum possible number under the circum- 
stances. 
2 Loew, O. Die chemische Energie der lebenden Zellen. Miinchen, E. Wolff, 
175 pP. 
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