PHYTOGENESIS. 261
But the following remarks, which in nature (who never, like a bad artist without a plan, fluctuates between the most opposite methods) would be, in the usual mode of treating it, an inexplicable contradiction and an absolute miracle, will serve for the decisive establishment of this view.
So soon as the secretion of this organized mass, the wood, takes place, for instance, we suddenly miss the influence of the law of formation, which, until then, had without exception directed the growth of the entire plant in all its parts. Here, so far as we are at present acquainted with the subject, there is no formation of cells within cells, here no expansion on all sides of the originally minute vesicle occurs, there is here no cyto- blast upon which the young might be developed ; but beneath the outermost layer of cells, which are comprised in the term bark, an organisable fluid is poured out, as it were, into a single, large, intercellular space, which fluid, as it seems, consolidates quite suddenly throughout its entire extent into a new, alto- gether peculiarly-formed tissue of cells, which are deposited one upon another, the so-called prosenchyma. Here, more- over, there is decidedly no formation of vascular bundles from cells of lower dignity, for all of them originate simultaneously and of their full size; and what has been called (spiral) vessels of the wood, is something which differs immensely from the spiral vessels of herbaceous plants, both in respect of their origin, and probably of their physiological signification also.[1] In like manner, no result has been obtained from the con- troversies which have been sometimes carried on with great warmth respecting the function of spiral vessels, nor could any be gained, because each party meant the spiral vessels of herbaceous plants, or of the wood, ad libitum, completely losing sight of the possibility that the two might be very different things. If, for instance, we examine the cambium in the earliest period at which it begins to acquire organisation,
- ↑ This position has undergone essential modifications, in consequence of subsequent researches which I have made with respect to the cambium, and which proved that a cambium, in the sense in which it had been previously used in physiology, namely, as denoting an amorphous formative fluid between the wood and bark, had no existence at all; that the wood and the bark, on the contrary, form one uninterrupted continuity, and their margin is merely denoted by a layer of delicately-walled, gelatinous cellular tissue.
