Gardeners’ Chronicle, (Ser. 3) 24: 288 (October 15, 1898)

The Reciprocal Action of Scion and Stock

IT lS a curious circumstance, that practical gardeners of the greatest experience of the generation now passing away, denied almost to a man that there is any action of the stock on the scion, or of the scion on the stock; and yet these men, and their predecessors, had been grafting and budding from time immemorial. They derived advantage from the process as a quick and convenient mode of propagation, but it is only comparatively quite lately that they have admitted that there are other benefits to be obtained. A pomologist grafts an Apple he wishes to propagate on the Paradise stock with the certainty that his Apple will be of more compact habit and of earlier and earlier fertility than if grown on the Crab or on its own roots. The vegetative system of the plant will be checked by the grafting, and by balancement organique, as the French say—by compensation, the development of flowers will be proportionately enhanced. Still, it is rare that a gardener will admit any further influence than what has been alluded to. He overlooks or ignores the many cases in which he grafts one Vine upon another with a view of curing some defect, such as cracking, or for some other cause, which renders his denial of reciprocal action somewhat inconsistent. It must be admitted that such effects are so rarely visible on the surface that they must be looked on as exceptional; but there is a great deal that we do not see, but which we may expect to see in the future.

The physiologist was also unwilling to admit that, as a rule, there was direct communication between stock and scion, but he recognised the exceptions, and found them, on investigation, more numerous than he had at first expected. These were the days when we were taught that the plant was made of little membranous bags or sacs, called cells, more or less filled with fluid when alive, but so perfectly closed and unbroken at the surface that no passage of fluid from one to the other was possible, except by means of filtration by "osmosis." By virtue of this process a thinner fluid passes through an intervening membrane to mix with a thicker fluid on the other side.

No doubt, this process of osmosis is a powerful aid in ensuring the movement of fluid in plants. A discovery made some few years ago by a Cambridge botanist, Mr. WALTER GARDINER, and since abundantly confirmed, has, however, thrown a new light on the subject. In the living cell there is, as everyone knows, a thick, semi-liquid substance, which is known as "protoplasm." In former days each cell was supposed to have had its mass of protoplasm so long as it was alive and active, but any passage of protoplasm from one cell to another, or any admixture of the plasm of one cell with that of another was considered impossible. Mr. GARDINER'S discovery consisted in the proof that there were in that portion of the cell-wall between two cells, extremely minute tubes opening up communication from one cell to another, and permitting the passage of threads of protoplasm from one cell to another. Now-a-days a plant, instead of being looked on as an aggregate of independent cells, is considered rather as an independent whole, consisting of cells which are in communication, real or potential, throughout the whole plant. Of course, such a discovery revolutionises vegetable physiology, and we may certainly look to this "continuity of protoplasm" to explain much of what is still mysterious in the matter of bud-variation (sporting) and grafting.

We have been led to these remarks by the perusal, in the Comptes Rendus of the French Academy of Sciences, of the experiments of M. LUCIEN DANIEL. Cabbages, he says, can be improved by grafting appropriately-selected sorts one upon the other, and by sowing the seeds of the scion (Creation de Variétés Nouvelles, par la greffe, April 30, 1898). Similarly variation in the common "Jack in the Hedge," Alliaria officinalis, may be obtained by grafting it on a Cabbage.

Pursuing his researches, M. DANIEL has grafted the wild Carrot on a cultivated form of stump Carrot. These two plants differ very materially, both in foliage and in the character of their roots. When grafted the wild Carrot grew well, utilising the reserves in the stock on which it was grafted, and ultimately produced seed larger than those of the checkplant grown for comparison. The seeds were sown side by side with some from the ordinary wild Carrot. The seedlings of the latter germinated in the usual manner, but those derived from the graft showed many differences which we have not room to cite here. Generally, we may say that the differences in the seedlings were manifested: 1, in the seed-leaves or cotyledons; 2, in the precocious development of seed; 3, a change in habit, colour, and hairiness; and 4, a swollen condition of the root, but without change of colour.

*panic, overreaction;
"genomic shock"

M. DANIEL’S experiments are recorded in the Comptes Rendus, July 11, 1898, and show the influence of the stock on the posterity of the graft. This influence determines not only variation in general, but a more or less complete admixture of the characteristics of the stock and of the scion, so that in the offspring of the scion a kind of disturbance (affolement*) arises resembling that caused by crossing or hybridisation.

From a practical point of view the experiments reveal the possibility of "improving" wild plants by grafting, and subsequently sowing the seeds from the graft, and selecting the seedlings in the ordinary way. M. DANIEL, does not tell us how he grafted his wild Carrot. Of one thing we are certain: no gardener or farmer in this country will think it worth his while to make such experiments, whilst the paucity of research-stations does not augur well for the experiment being tried here at all. Thus, whatever comes of it, our neighbours will get the benefit, and we shall have to pay for what we might have made ourselves.

Daniel bibliography