=Many Pathways of Conduction Not Established at Birth.--=As we have already seen the evidence is that many of the neural pathways are not yet fully established at birth, and there is some indication that routes once opened may be altered. To what degree this has bearing on behavior is still unknown, but since neurologists attribute so much importance to the richness and the associations of the cell-outgrowths, it is evident that this increase in the number of pathways after birth with possible alternatives of connections may be a very important factor in the modification of behavior. Yet, on the other hand, we are completely in the dark as to what extent these later associations are predetermined in the earlier cells. =The Extent of the Zone That Can Be Modified Is Unknown.--=There is little doubt that many of the paths of action are already firmly established. Others, although not irrevocably fixed, offer the least resistance and would "naturally" be taken if not counteracted or modified by the more or less artificial development and fixation of other paths through cultivation and habit. Yet others perhaps are largely neutral; they still await the initial decisive push which "choice" or external environment may mete out to them. As trainers of youth all that is left that we can do is to attempt to develop in certain ways the elements of this indefinite, impressible zone. Unfortunately, we must labor in the dark to a great extent as we have all too little indication of which the malleable factors of intellect and conduct are. We can only infer from long, intelligent and sympathetic observation of children in successive stages of their development. It is only by having clearly in mind the nature of our problem that our conclusions will finally come to be of enhanced practical value in the training of children. Observation to the present time clearly indicates that many children are strongly predisposed this way or that "as the sparks fly upward." This is a point too frequently overlooked by educators. They are often unduly actuated by the other piece of the truth that, "as the twig is bent the tree inclines." They sometimes fail to realize that after all the tree remains the same kind of a tree. If an apple tree, while it may be bent from the normal path of development, it can not produce other fruit than apples. Just how much the destiny of man can be influenced by training and the exercise of his own will power is the fundamental question not only of pedagogy but of ethics as well. For if man's rational judgments are markedly conditioned by his neural make-up then the volitional judgments which underlie conduct are likewise conditioned since they are inextricably intermingled with his reason. We must believe that to a considerable extent emotional expression, as well as other mental functions, is due to hereditary dispositions of the neurons in the various parts of the brain.