CONTINUITY IN EVOLUTION. 331 
and germinal continuity, or their analogues in the psychical 
order of being, are rendered conceivable. Consciousness is 
regarded as a developed form of sentience. But the sentience 
is wholly hypothetical. It is at best a “may be,” and its 
existence is incapable of proof. And science is rightly im- 
patient of hypotheses the validity of which .cannot in any way 
be verified. Our safest course, therefore, is to accept that 
which is common to both hypotheses, evolutional continuity, 
and for the rest to be content with a confession of ignorance. 
We have already drawn attention to the fact that mere 
sentience, if it exists, has no power of guidance over organic 
behaviour ; but consciousness, when it emerges, is a concomi- 
tant of nervous processes which determine the nature and 
direction of such nerve-changes as are the antecedents of 
intelligent behaviour. The steps by which this control is 
established are unknown. It is, indeed, probable that con- 
scious guidance arises as an accompaniment of the differentia- 
tion of controlling centres from the automatic centres of the 
nervous system ; but of how this takes place we are as igno- 
rant as we are of many other differentiations in the course 
of embryological development and evolutional progress. Of 
those nervous arrangements within the brain which are the 
physiological concomitants of the far later mental processes of 
reflection, abstraction, generalization, and the formation of 
ideals, we are, if it be possible, even yet more profoundly 
ignorant. Nor would it serve any good purpose to indulge in 
speculation where there are not even the data to enable us so 
much as to hazard a probable guess. The utmost we are 
justified in attempting is to show how organic behaviour leads 
up to and affords the requisite data for the exercise of intelli- 
gence, and how both supply the necessary preliminary stages 
in the development and evolution of what, following Dr. 
Stout, we have termed ideational process. This we have 
endeavoured to do in preceding pages; and all that is now 
required is to conclude our inquiry with a brief summary by 
which the results, as affording some basis for evolutional con- 
tinuity, may be focussed. 2 
