R. A. Emerson

The Nature of Bud Variations as Indicated by Their Mode of Inheritance

THE title limits this accounit to such bud variations as have been studied critically with respect to their iniheritance in sexual reproduction. The further limitation of time makes it necessary that I choose from among such studies certain cases to serve as illustrations of the several types of bud variation. I shall, therefore, attempt no complete review of the researches bearing on the problem at hand. A survey of published accounits of bud-variation studies shows that as yet comparatively little is definitelv known of the real nature of these vegetative sports. It seems not unlikely, however, that to poilit out some of the problems suggested by these studies anid, where possible, to note modes of attack may serve the purpose of this symposium quite as well as a rehearsal of knowii fadts and their interpretation. As here used, the term bud variation is syioillv11ous with vegetative as contrasted with seminal variation. The term somatic variation may also be employed to the same effect, provided it is niot thereby intended to exclude cases in which the germ tract as well as the soma is involved. At the outset, however, there must be imposed on any of these terms, for the purpose of this discussionl at least, the limitation that the variation involves a change in the genetic constitution of the parts affected. The expressions somatic mutation anid somatic segregation are specific terms and as such are niot to be used interchangeably with the more general terms somatic, vegetative, or bud variations. Moreover, to speak of a particular vegetative variation as a case of sonmatic muta1 Paper No. 94, Departmiient of Plant Breedinig, Cornell University, Ithaca, Nn11 -vlk--