vou. u.] Colors of West Coast Mammals. 205 
the same continuing through successive generations, it is evident 
that the inheritance in each individual offspring is infinitely mul- 
tiple. Now the tendency to variation in offspring is in proportion 
to the multiplicity of the inheritance; for among the infinite num- 
ber of slightly different characters, as it were offered for inheritance 
in every generation, some individuals will inherit more of one and 
some more of another character. In a word, sexual generation, 
by multiple inheritance, tends to variation of offspring and thus 
furnishes material for natural selection.” This passage might seem 
to have a slight teleological flavor, as if this difference in sex were 
instituted in order that we might have a greater amount of vari- 
ability, whereas the author simply means to imply, it seems to me, 
that a greater amount of variability is incident to this difference 
between the sexes. However, this suggestion of Prof. Le Conte’s 
merely shows us how a difference in the sexes may increase the ma- 
terial upon which natural selection may work, but does not show how 
new material may be created. Just here it is of importance to take 
note of two of the laws of heredity as stated by Haeckel:* ‘‘A 
third law of conservative transmission may be called the law of 
sexual transmission, according to which each sex transmits to the 
descendants of the same sex peculiarities which are not inherited 
by the descendants of the othersex. * * * A fourth law of 
transmission, which has here to be mentioned, in a certain sense 
contradicts the last, and limits it, viz: the law of mixed or mutual 
(amphigonous) transmission. This law tells us that every organic 
individual produced in a sexual way receives qualities from both 
parents, from the father as well as from the mother.’’ 
In examining the series of Spermophilus grammurus atricapillus 
it is found that there is quite a well marked average difference be- 
tween the sexes in regard to color, the males being so much darker 
than the females that I was enabled to separate the specimens of the 
two sexes, making but one error, when a very dark female was 
placed in the series with the males. It is now necessary, before 
continuing, to call attention to one more fact, stated by Geddes & 
Thomson,} that: ‘A review of the animal kingdom, or a perusal 
of Darwin's pages will amply confirm the conclusion that on an 
oe History of Creation, i, pp. 209-210. 
tEvolution of Sex, p. 15. 
