In consequence of this double sense in which the term "acquired characters" may be used, great confusion may and does occur. If the protoplasm be compared to a machine, and the external conditions to the hand that works the machine, then it may be said that, as the machine can only work in one way, it can only produce one kind of result (genetic character), but the particular form or quality (Lamarckian "acquired character") of the result will depend upon the hand that works the machine (environment), just as the quality of the sound produced by a fiddle depends entirely upon the hand which plays upon it. It would be improper to apply the term "mutation" to those genetic characters which are not new characters or new variants of old characters, but such genetic characters are of the same nature as those characters to which the term mutation has been applied. It may be noticed in passing that it is very questionable if the modern biologist has acted in the real interests of science in applying the term mutation in the sense in which he has applied it. The genetic characters of organisms come from one of two sources: either they are old characters and are due to the action of what we call inheritance or they are new and are due to what we call variation. If the term mutation is applied to the actual alteration of the machinery of the protoplasm, no objection can be felt to its use; but if it be applied, as it is, to the product of the action of the altered machine, viz. to the new genetic character, it leads to confusion. Inheritance is the persistence of the structure of the machine; characters are the products of the working of the machine; variation in genetic characters is due to the alteration (mutation) in the arrangement of the machinery, while variation in acquired characters (Lamarckian) is due to differences in the mode of working the machinery. The machinery when it starts (in the new zygote) has the power of grinding out certain results, which we call the characters of the organism. These appear at successive intervals of time, and the orderly manifestation of them is what we call the life-history of the organism. This brings us back to the question with which we started this discussion, viz. what is the relation of these variations in structure, which successively appear in an organism and constitute its life-history, to the mutational variations which appear in different organisms of the same brood or species. The question is brought home to us when we ask what is a bud-sport, such as a nectarine appearing on a peach-tree? From one point of view, it is simply a mutation appearing in asexual reproduction; from another it is one of these successional characters ("growth variations") which constitute the life-history of the zygote, for it appears in the same zygote which first produces a peach. Here our analogy of a machine which only works in one way seems to fail us, for these bud-sports do not appear in all