Pangenesis: Graft-Hybrids

Abstract

IN your last number Mr. Ranyard brings forward an objection to Mr. Darwin's theory of Pangenesis on the ground that the grafting of a bud on a stock of a different species does not produce a hybrid offspring. I am not about to defend the doctrine of Pangenesis, which appears to me incapable alike of proof and of disproof. It is, however, a well-known fact that the siock does affect the scion, and vice versâ. In Prof. Henfrey's “Elementary Course of Botany” (Dr. Masters's edition) he says, “A certain amount of physiological influence of the stock over the scion is shown to exist by such facts of horticultural experience as that the fruit of the pear is smaller and more highly coloured when ‘worked on’ the quince and medlar than when grafted on pear-stocks, and is earlier when worked on the mountain-ash.” The well-known instances of the communication of variegation from the scion to the stock in Abutilon, recorded by Prof. Moiren and others, are considered cases of contagious disease; but what is the theory ot contagion but that the blood or other “fluid” of an animal or plant is affected by emanations call them “gemmules” or what you will, from another individual? The same writer records an instance which he considers well authenticated of the production of the hybrid Cytisus Adami by the grafting of C. purpureus on C. laburnum.