PHYTOGENESIS. 261 
But the following remarks, which in nature (who never, like 
a bad artist without a plan, fluctuates between the most oppo- 
site methods) would be, in the usual mode of treating it, an inex- 
plicable 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.' 
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 exist- 
ence 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, gela- 
tinous cellular tissue. 
