It may be said, however, that some reference to the conscious aspect of instinctive behaviour is implied by saying that the acts are performed without instruction or experience. But the reference at present is wholly negative. We may say, as the result of observation, that instinctive acts are performed under such circumstances as exclude the possibility of guidance in the light of individual experience, and render it in the highest degree improbable that there exists any idea of the end to be attained. But this is a very different position from that of asserting the presence of a positive faculty or propensity which impels an animal to the performance of certain actions. This it is which, from the observational point of view, is unnecessary. For the reference of a given type of observed behaviour to a “propensity” so to behave or to a “faculty” of thus behaving, is no more helpful than the reference of the development of any given type of structure to a “potentiality” so to develop. We may, therefore, without loss of precision, simplify Spence’s definition by stating that instinctive behaviour is independent of instruction and experience, and tends to the well-being of the individual and the preservation of the species. Let us next consider the clause which affirms that instinctive behaviour is prior to experience. This is well in line with the distinction now drawn by biologists between congenital and acquired characters. It refers them to the former category, and implies that the organic mechanism by which they are rendered possible is of germinal origin. This is not, however, universally admitted. Professor Wundt, for example, approaching the subject from the point of view afforded by the study of man and the higher animals, gives to the term a wider meaning, and so defines instinct as to include acquired habits. “Movements,” he says,[26] “which originally followed upon simple or compound voluntary acts, but which have become wholly or partly mechanized in the course of individual life, or of generic evolution, we term _instinctive_ actions.” In accordance with this definition, instincts fall into two groups. Those “which, so far as we can tell, have been developed during the life of the individual, and in the absence of definite individual influences might have remained wholly undeveloped, may be called _acquired_ instincts.” They have become instinctive through repetition. “To be distinguished from these acquired human instincts are others which are _connate_.” Now, there can be no question that behaviour which has become habitual through frequent repetition is frequently, in popular speech, described as instinctive. We hear it said that the experienced cyclist guides his machine instinctively. And the word is similarly used in many like cases. But we shall find it conducive to precision and clearness of thought to emphasize the distinction between what is acquired in the course of life and what is congenital in the race. And to this