Page:Proceedings of the Royal Society of London Vol 1.djvu/141

Rh and the horizontal branches would hence soon extend so far and be- come so bulky, as to render it impossible for the trunk to support them. The principal ofﬁce here ascribed to the horizontal and spread- ing branches, is to nourish and support the blossoms and fruit, or seed; little or nothing of the sap being here returned to the parent tree, and hence very feeble powers being Wanted in the returning system.

Our author had long entertained an opinion that the ascending ﬂuids in the albumum and central vessels are everywhere the same, and that the leaf-stalk, the tendril of the vine, the fruit-stalk, and the succulent point of the annual shoot, might in somermeasure be substituted for each other: experiments have proved his conjecture in many instances to be well founded. In several of these experi- ments, leaves continued to perform their oﬂice when grafted on the fruit-stalk, the tendril, and the succulent shoot of the vine; and the leaf-stalk, the tendril, and the fruit-stalk, equally supplied a branch grafted upon them with nourishment.

0n examining the manner in which wounds in trees become co- vered, an additional proof was found, that the medullary processes, namely, the knobs of wood formed at the junction of a grafted bud, with the stock in which it is inserted, are like every other part of the wood generated by the bark. This is mentioned in contradiction to the opinion still entertained, that the hardest, most durable, and most solid part of the wood, is composed of the soft, cellular, and perishable substance of the medulla. Lastly, some observations are stated, which seem to imply that the sap in its descent may undergo some modiﬁcation which ﬁts it more effectually to produce wood.

A few remarks on the formation of buds in tuberous rooted plants beneath the ground, are added by way of appendix. These, if the above theory be true, must be formed of matter which has descended from the leaves through the bark. An experiment was made on a potatoe plant by intersecting its runners which connect the tubers with the parent plant, and immersing their ends in a decoction of logwood. In about twenty hours it was found that the decoction had indeed passed along the runners in both directions, but that none had entered the vessels of the parent plant. This result was not un- expected to the author, he being well aware that the matter by which the growing tuber is fed must descend from the leaves through the bark, and that bark cannot absorb coloured infusions.

In April last, a printed notice was circulated concerning a substance to which the name of Palladium, or new silver, was assigned, and of which samples were offered for sale at Mr. Forster’s, in Gerrard Street, Soho. A discovery of such importance did not fail to