THE BIOLOGICAL ASPECT 305 
the leading senses—but they are leaders without a following ; 
they have only a very limited contpany to conduct into action. 
The company is there, on the further side of the severance, 
but they have lost touch with it. They know not what it is 
doing, and have therefore neither the data nor the executive 
power to guide its manceuvres in the field of behaviour. 
They can form maimed coalescent situations, but they are 
as impotent as a mere theorist devoid of all power of practical 
application. We need not, however, follow the theme further. 
We need only add that, could we isolate tracts of nervous 
tissue in the lower brain-centres of such a cerebral animal, 
we should find that subsidiary co-ordinations would belong, 
as a physiological heritage, to these isolated fragments. 
The conclusions we may draw, then, with regard to the 
evolution of behaviour, as viewed in its physiological aspect, 
are that it is, in its simplest expression and in its most 
complex, conditioned by sufficient unity of purpose to meet 
the biological end of survival; that the complex unity of 
purpose may be analyzed into a multiplicity of subsidiary 
processes each with its subsidiary unity of purpose; and that 
the psychological coalescence which gives unity to experience 
under the guidance of the leading senses, is paralleled in 
a physiological coalescence within the nexus of the nervous 
system. 
II.—Tue Bronoaican ASPECT 
The biological aspect of behaviour—its relation to biological 
ends—has so often come under our consideration in the fore- 
going chapters that little need be added in this section : and 
that little may be most appropriately devoted, first to the 
question whether consciousness does influence behaviour ; and 
secondly, this being accepted, to the importance of the réle 
that is played by the development of conscious situations in 
securing, in the higher animals, the biological end of racial 
preservation. 
That this end is secured without the aid of consciousness 
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