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President of the Horticultural Society of London. He says (I reprint from his works, as follows):—
"PAPER ON VEGETABLE PHYSIOLOGY.–I. OBSERVATIONS ON THE GRAFTING OF TREES.
[Read before the Royal Society, April 30th, 1795.]
The disease from whose ravages apple and pear trees suffer most is the canker; the effects of which are gennerally first seen in the winter, or when the sap is first rising in the spring. The bark becomes discoloured in spots, under which the wood, in the annual shoots, is dead to the centre; and, in the older branches, to the depth of the last summer's growth. Previous to making any experiments, I had conversed with several planters, who entertained an opinion, that it was impossible to obtain healthy trees of those varieties which flourished in the beginning and middle of the present century, and which now form the largest orchards in this county (Herefordshire). The appearance of the young trees which I had seen, justified the conclusion they had drawn; but the silence of every writer on the subject of planting, which had come in my way, convinced me it was a vulgar error, and the following experiments were undertaken to prove it so.
I suspected that the appearance of decay in the trees I had seen lately grafted, arose from the diseased state of the grafts, and concluded that if I took scions or buds from trees grafted in the year preceding, I should succeed in propagating any kind I chose. With this view, I inserted some cuttings of the best wood I could find in the old trees, on young stocks raised from seed. I again inserted grafts and buds taken from these on other young stocks, and, wishing to get rid of all connexion with the old trees, I repeated this six years; each year taking the young shoots from the trees last grafted. Stocks of different kinds were tried; some were double-grafted, others obtained from apple-trees which grew from cuttings, and others from the seed of each kind of fruit afterwards inserted on them. I was surprised to find that many of these stocks inherited all the diseases of the parent trees.
The wood appearing perfect and healthy in many of my last-grafted trees, I flattered myself that I had succeeded; but my old enemies, the moss and canker, in three years convinced me of my mistake. Some of them, however, trained to a south wall, escap-
