THE BIOLOGICAL ASPECT a1 
In sexual selection by preferential mating, even if we follow 
Professor Groos in believing that it isa special mode of natural 
selection, the conscious situation is essential. If we accept the 
theory in any form, we must regard the adornments, antics, 
and display of the male as an appeal in some way to the 
consciousness of the female, whatever particular form the 
effects in that consciousness may take, whether the appeal 
evoke a sense of beauty, or simply be a means of exciting to 
the consummation of the natural end of courtship. Even if 
we follow Mr. Wallace in regarding plume and song as “ re- 
cognition marks,” it is only by their appeal to consciousness in 
this way, if in no other, that they are of any biological value. 
And this, of course, applies equally to the whole range of his 
theory of recognition marks—their sole utility lies in their 
being a stimulus to consciousness through which the end of 
recognition is secured. So, too, not only the specialized 
behaviour which we dignify by the name of “courtship,” but 
every case in which mate is drawn to mate through sight, 
smell, hearing—any of the leading senses—testifies to the im- 
portance of consciousness in furthering an end of supreme 
biological importance. 
And if, as Darwin urged, the “law of battle’ among the 
males co-operates with preferential mating, as we can hardly 
deny, in securing strong, vigorous, and healthy fathers of the 
generation they beget, here, too, consciousness is an important 
factor. Can we conceive a “law of battle” among unconscious 
beings? If success in the combat were a mere matter of brute 
strength, it would imply some consciousness in its dull exercise. 
But it is more. It is also a trial of skill. Were it not so our 
forefathers would not have spent hours in watching a cock-fight, 
or laid heavy odds on their particular ‘‘ fancy.” 
We need not labour the theme. In the search for food or 
a nesting site, in the capture of prey and escape from enemies, 
in all that demands attention, and in all that necessitates 
practice, in what M. Houssay calls “the industries of animals,” 
and in that which Mr. Hudson calls “‘ tradition,” consciousness 
has a part to play. Even plants unconsciously appeal to the 
