V. On the direction of the radicle and germen during the vegetation of seeds. By Thomas Andrew Knight, Esq. F. R. S. In a letter to the Right Hon. Sir Joseph Banks, K. B. P. R. S

Abstract

My Dear Sir, It can scarcely have escaped the notice of the most inatten­tive observer of vegetation, that in whatever position a seed is placed to germinate, its radicle invariably makes an effort to descend towards the centre of the earth, whilst the elongated germen takes a precisely opposite direction; and it has been proved by Du Hamel that if a seed, during its germination, be frequently inverted, the points both of the radicle and germen will return to the first direction. Some naturalists have supposed these opposite effects to be produced by gra­vitation; and it is not difficult to conceive that the same agent, by operating on bodies so differently organized as the radicle and germen of plants are, may occasion the one to descend and the other to ascend. The hypothesis of these naturalistsdoesnot, however, appear to have been much strengthed by any facts they were able to adduce in support of it, nor much weakened by the argu­ments of their opponents; and therefore, as the phenomena observable during the conversion of a seed into a plant are amongst the most interesting that occur in vegetation, I commenced the experiments, an account of which I have now the honour to request you to lay before the Royal Society.