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 contaminate, 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]