In this same connection another question needs to be discussed. It is assumed by several botanists that in a normal plant the latent shoots or buds along the stem do not develop so long as the terminal shoots are growing, because the latter use up all the food material that is carried to that region. If the terminal bud is destroyed the lateral shoots then burst forth, in consequence, it is assumed, of the excess of food stuff that now comes to them. I do not believe that the phenomena can be so easily explained. If a piece of a plant is cut off, the leaves removed, and the piece suspended in a moist chamber and kept _in the dark_, the lateral buds at the apex will begin to develop. If we assume that the piece cannot develop any new food substance in the dark, then it contains just the same amount as it did while a part of the plant, and yet that amount is ample for the development of the lateral buds. Moreover, only the more apical buds develop; but if the piece is then cut in two, the apical buds of the basal piece, that had remained undeveloped, will now develop. How can this be explained by the amount of food substances in the piece? If it is assumed that in the normal plant the food substances flow only to the growing points, and the buds are out of the main current and fail in consequence to develop, it can be shown that this idea also fails to explain certain results. Vöchting has found, for example, that if an incision is made _below_ a bud and the piece containing the bud be lifted up somewhat from the rest of the piece, remaining attached only at its anterior end, the bud will begin to develop. In this case the conditions preclude an accumulation of food substances in the piece, and the bud is even farther removed than at first from the main current, yet it begins to develop. We shall find, I think, that the idea of food stuffs fails to explain some of the simplest phenomena, and while it need not be denied that under certain conditions the presence or accumulation of food materials may produce certain definite results, yet such food stuffs seem to play a very subordinate part as compared with certain other internal or innate factors. CHAPTER V REGENERATION AND LIABILITY TO INJURY There is a widespread belief amongst zoologists that a definite relation exists between the liability of an animal to injury and its power of regeneration. It is also supposed that those individual parts of an animal that are more exposed to accidental injury, or to the attacks of enemies, are the parts in which regeneration is best developed, and conversely, that those parts of the body that are rarely or never injured do not possess the power of regeneration.