Directive Coloration in Animals. 205 
to intensify certain lateral and caudal markings, or even to produce 
in them sexual differences. We should naturally expect this to be 
as manifest in nocturnal animals as anywhere. To this cause we 
are disposed to refer the different colors of the wing-spots of night- 
hawks and other Caprimulgide: In the males they are white, while 
in the females they are rufous. Possibly, some of the cases which 
Darwin considers the results of sexual selection transferred from 
the male to the female may be referred to this influence. 
Another relation may, presumably, modify ‘directive coloration 
to a considerable degree, especially in animals which, though roving 
the fields themselves, secrete their young. Deer, swine, lions, ete., 
may be taken as examples of this. The vivid markings upon the 
young may’assist much in the care which the mother gives in the 
dim light of the hiding-place and at night. This explanation does 
not necessarily conflict with the more commonly received opinion 
—that they are the effect of heredity, revealing the coloration of 
Some remote ancestor. It suggests, rather, the further inference 
that that ancestor was either gregarious and living on open plains, 
or else was more solitary and prowling, skulking in dim lights. 
Our theory would offer a rational explanation for its persistence in 
the earlier stages of living species. 
It will be noticed that we have drawn our illustrations entirély 
from the mammals and birds. We would not imply that our theory 
is limited to these. Insects, fishes and reptiles may afford equally 
good examples, 
We would remark, in concl usion, that this sketch does not attempt 
to give details more than may be necessary to present our view in- 
telligibly. Of course, we recognize the validity of the theory of 
typical coloration consisting of those primal tints and patterns which 
have been ascribed to the combined action of chemical, physical and 
vital forces only ; also the theories of protective and ornamental 
colorations, which have been evolved from the typical by the action 
of natural and sexual selection. We do not profess to be able to 
refer every tint and pattern of coloration to its predetermining con- 
dition or advantage. That would be well-nigh impossible. But if 
enough has been given and with sufficient discrimination to satisfy 
_ Most minds, that adaptation for directive purpose is a real advan 
which has been decidedly effective in determining the coloration of 
mals we are content. ? 
