The oldest notion is that the production of a nectarine on a peach-tree is due to the direct action of pollen from some nearby nectarine-tree on the ovary of the peach. This theory, wholly at variance with present knowledge, is also discredited by the many instances in which the sports occur when the two fruits are not growing in the same neighborhood or even region. Thus, within ten years, several cases of nectarines on peach-trees have occurred in this State where the nectarine is scarcely known. Besides, crossing these fruits shows no direct effect of pollen--as is true with nearly all other plants. Still further, when a branch of a peach has borne a nectarine it usually goes on year after year producing nectarines; and certainly impregnation of a flower by foreign pollen could not so profoundly modify a branch. There is so little foundation for this belief that it would not be mentioned were it not that many fruit-growers still look to the action of pollen as the explanation of the phenomenon. Another, and a much more probable explanation, is that every sporting peach or nectarine-tree is a more or less remote hybrid. There is a growing belief that species are fixed and that crossing is the only source of new seed- or bud-forms. Certainly all who have crossed plants in any considerable numbers know that hybridity is at least one cause, and a frequent one, of mutations. It is possible that sometime in the past the peach and the nectarine were crossed, the offspring showing no trace of the cross, and that now there is an occasional disassociation of the characters brought together by such crossing. There are several objections to this hypothesis. One is that two forms sufficiently distinct to induce so striking a variation as a nectarine from a peach, must have differed in tree as well as in fruit-characters and that these differences would crop out just as smoothness of fruit so frequently does. Another, and less potent objection, is that the nectarine has never been found wild, that it never becomes naturalized, that it is shorter-lived and less vigorous and behaves in general like an artificial plant.