Am. Jour. Sci., 8:84-85 (1899)

Variation under grafting, and the heredity of acquired characters; by L. DANIEL. Ann. sc. nat., April and May, 1899.—M. Daniel has conducted his interesting studies in regard to the effect of the scion on the stock and the origination of variation thereby, for almost ten years. He has made his work logically comparative, and, has, in this way, contributed some very important facts to the literature of the subject. He insists that a broad distinction must be drawn between the behaviour of a cutting and an implanted graft. The former has in the soil the nutritive conditions of its parent; the graft is tributary at once to the stock in which it is fastened and places it at once under contribution. It is not a matter of parasitism, for the scion, with its leaves, is to aid in providing elaborated matters for the stock, but, nevertheless, it demands crude materials from the soil through and from the stock.

The graft and grafted plant must be regarded as a case under the general law that change of environment may, or rather, must modify form and structure. Variation from grafting is a function of modifications brought about in the general nutrition of the two plants. This modification may be direct as in the case of the somatic union, or indirect as in the instance of the blending of the germ-plasma from two sources. The author makes the statement that the germ-plasma can be affected from the first generation in the graft, contrary to the law laid down by Weissmann.

The graft and stock introduce variations which may be very slight and liable to be overlooked, but carefully considered these variations are seen to be generally conservative. And as the graft can convey in perpetuity an accidental variation, these accidental variations of the second order can themselves be transmitted effectively, If the influence of a graft on a plastic soma may be strong enough to lead to the origination of a variety, as this research has shown to be possible, we have here in the process of grafting a valuable appliance which is capable of wide utilization in initiating new forms as well as in preserving old ones. The action of grafting on the reproductive elements and on the transmission of these new characters opens up to seed cultivators an inviting held of practice. It must not be overlooked that, as matter of fact, variation does not come in the grafted plants themselves, but manifests itself in the embryo alone. The author emphasizes the importance of this process of grafting in the improvement of sorts, and shows that such work can be carried on with the utmost system. The process is by no means, confined to woody plants, but, as the investigation shows abundantly, it is applicable to a wide range of herbaceous species. Merely from a utilitarian point of view, the research is a valuable contribution, while regarded from a purely scientific standpoint it possesses deep interest. The work already done is of consequence, but its best service is in opening up new practical questions.—G.L.G.

Daniel bibliography