most convincing genetic view of these phenomena throws the instinctive proclivities into close relation with the tropismatic sensibilities and brings them, in the physiological respect, into the same general class with the latter.6 If taken uncritically and in general terms this view would seem to carry the implication that the instincts should be discrete and discontinuous among themselves somewhat after the same fashion as the tropismatic sensibilities with which they are in great measure bound up; but on closer scrutiny such a genetic theory of the instincts does not appear to enforce the view that they are to be conceived as effectually discontinuous or mutually exclusive, though it may also not involve the contrary, - that they make a continuous or ambiguously segmented body of spiritual elements. The recognised tropisms stand out, to all appearance, as sharply defined physiological traits, transmissible by inheritance intact and unmodified, separable and unblended, in a manner suggestively like the “unit characters” spoken of in latter day theories of heredity.7
While the instinctive sensibilities may not be explained as derivatives of the tropisms, there is enough of similarity in the working of the two to suggest that the two classes of phenomena must both be accounted for on somewhat similar physiological grounds. The simple and more narrowly defined instinctive dispositions, which have much of the appearance of immediate reflex nervous action and automatically defined response, lend themselves passably to such an interpretation, - as, for example, the gregarious instinct, or the instinct of repulsion with its accompanying emotion of disgust. Such as these are shared by mankind with the other higher animals on a fairly even footing; and these are relatively simple, immediate, and not easily sophisticated or offset by habit. These seem patently to be of much the same nature as the tropismatic sensibilities; though even in these simpler instinctive dispositions the characteristic quasi-tropismatic sensibility distinctive of each appears to be complicated with obscure stimulations of the nerve centres arising out of the functioning of one or another of the viscera. And what is true of the simpler instincts in this respect should apply to the vaguer and more complex instincts also, but with a larger allowance for a more extensive complication of visceral and organic stimuli.
Whether these subconscious stimulations of the nerve centres through the functioning of the viscera are to be conceived in terms of tropismatic reaction is a difficult question which has had little attention hitherto.
But in any case, whatever the expert students of these phenomena may have to say of this matter, the visceral or or-ganic stimuli engaged in any one of the instinctive sensibilities are apparently always more than one and are usually somewhat complex. Indeed, while it seems superficially an easy matter to refer any one of the simple instincts directly to some certain one of the viscera as the main or primary source from which its appropriate stimulation comes to the nerve centres, it is by no means easy to decide what one or more of the viscera, or of the other organs that are not commonly classed as viscera, will have no part in the matter.
It results that, on physiological grounds, the common run of human instincts are not to be conceived as severally discrete and elementary proclivities. The same physiological processes enter in some measure, though in varying proportions, into the functioning of each. In instinctive action the individual acts as a whole, and in the conduct which emerges under the driving force of these instinctive dispositions the part which each several instinct plays is a matter of more or less, not of exclusive direction. They must therefore incontinently touch, blend, overlap and interfere, and can not be conceived as acting each and several in sheer isolation and independence of one another. The relations of give and take among the several instinctive dispositions, therefore - of inosculation, “contamination” and cross purposes-are presumably slighter and of less consequence for the simpler and more apparently tropismatic impulses while on the other hand the less specific and vaguer instinctive predispositions, such as the parental bent or the proclivity to construction or acquisition, will be so comprehensively and intricately bound in a web of correlation and inter-dependence - will so unremittingly con-taminate, offset or fortify one another, and have each so large and yet so shifting a margin of common ground with all the rest - that hard and fast lines of demarcation can scarcely be drawn between them. The best that can practically be had in the way of a secure definition will be a descriptive characterisation of each distinguishable propensity, together with an indication of the more salient and consequential ramifications by which each contaminates or is contaminated by the working of other propensities that go to make up that complex of instinctive dispositions that constitutes the spiritual nature of the race. So that the schemes of definition that have hitherto been worked out are in great part to be taken as arrangements of convenience, serviceable apparatus for present use, rather than distinctions enforced at all points by an equally sharp substantial discreteness of the facts.8 This fact, that in some measure the several instincts spring from a common ground of sentient life, that they each engage the individual as a whole, has serious consequences in the domain of habit, and therefore it counts for much in the growth of civilisation and in the everyday conduct of affairs. The physiological apparatus engaged in the functioning of any given instinct enters in part, though in varying measure, into the working of some or of any other instinct; whereby, even on physiological grounds alone, the habituation that touches the functioning of any given instinct must, in a less degree but pervasively, affect the habitual conduct of the same agent when driven by any other instinct. So that on this view the scope of habit, in so far as it bears on the instinctive activities, is necessarily wider than the particular concrete line of conduct to which the habituation in question is due.
The instincts are hereditary traits. In the current theories of heredity they would presumably be counted as secondary characteristics of the species, as being in a sense by-products of the physiological activities that give the species its specific character; since these theories in the last resort run in physiological terms. So the instinctive dispositions would scarcely be accounted unit characters, in the Mendelian sense, but would rather count as spiritual traits emerging from a certain concurrence of physiological unit characters and varying somewhat according to variations in the complement of unit characters to which the species or the individual may owe his constitution. Hence would arise variations of individuality among the members of the race, resting in some such manner as has just been suggested on the varying endowment of instincts, and running back through these finally to recondite differences of physiological function. Some such account of the instinctive dispositions and their relation to the physical individual seems necessary as a means of apprehending them and their work without assuming a sheer break between the physical and the immaterial phenomena of life.
Characteristic of the race is a degree of vagueness or generality, an absence of automatically determinate response, a lack of concrete eventuality as it might be called, in the common run of human instincts.
This vague and shifty character of the instincts, or perhaps rather of the habitual response to their incitement, is to be taken in connection with the breadth and variability of their physiological ground as spoken of above. For the long-term success of the race it is manifestly of the highest value, since it leaves a wide and facile margin of experimentation, habituation, invention and accommodation open to the sense of workmanship.
At the same time and by the same circumstance the scope and range of conventionalisation and sophistication are similarly flexible, wide and consequential. No doubt the several racial stocks differ very appreciably in this respect.
The complement of instinctive dispositions, comprising under that term both the native propensity and its appropriate sentiment, makes up what would be called the “spiritual nature” of man - often spoken of more simply as “human nature.” Without allowing it to imply anything like a dualism or dichotomy between material and immaterial phenomena, the term “spiritual” may conveniently be so used in its colloquial sense. So employed it commits the discussion to no attitude on the question of man’s single or dual constitution, but simply uses the conventional expression to designate that complement of functions which it has by current usage been employed to designate.
The human complement of instincts fluctuates from one individual to another in an apparently endless
