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 258 CONTRIBUTIONS TO

success. My researches also with respect to this newly-arising formative layer between bark and wood are by no means concluded.

Before, however, I proceed to communicate my observations on this subject, it is necessary once more to take up the question of the individuality of plants. I have already remarked above that, in the strictest sense of the word, only the separate cell deserves to be called an individual. If we go a step further, we might define each axis with its lateral organs to be individual beings. If, however, we disregard this circumstance of the plant being composed of cells and similar axes, and conceive the term individual, as applied to the organic world, to signify a body which cannot be divided into two or more similar ones without the abolition of its idea of totality, and whose vital process has a fixed point of commencement and termination in definite periodicity, it thence follows that the herbaceous (planta annua) and the true biennial plants, which flower in the second year, and then die off entirely, are the only ones which can be regarded as individuals in the vegetable kingdom. The idea of individual life also necessarily requires as a characteristic that individual death should be a condition of the organization itself. But where such a death does not take place as a final termination from internal necessity, as an internal preconditioned cessation of the organizing force, there also must individuality be out of the question. This is the case, however, only in the above-mentioned plants, and from them solely, therefore, as from the prototype, must we set out, in all researches into the nature and life of the vegetable organism.

In order to facilitate the transition to what is to follow, I will now proceed to the exposition of the two different modes of propagation. It either takes place by a process which has hitherto been called impregnation in plants, and to which a sexual difference has been ascribed (Wiegmann’s Archiv, 1837, vol. i, p. 290, &c.), or by division; the plant, for instance, developing on itself a perfectly similar individual, and then at an appointed time dismissing it. This latter, the formation of so- called bulbilli, &c. occurs, together with the former, in only a small number of plants. We must, however, make ourselves somewhat more intimately acquainted with it. This formation,