PHYTOGENESIS. 261 



Hut the following remarks, which in nature (who never, lil. 

 a bad artist without a plan, fluctuates between the mod oppo- 

 site methods) would be, in the usual mode of tr< ating it, an Inex- 

 plicable contradiction and an absolute miracle, will serve for the 



decisive establishment of tins 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 pari Hen , 

 so far as we are at present acquainted with the subject, there is 

 no formation of cells within cells, here no expansion on all sid( - 

 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 arc 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 tin- 

 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 ho verj 

 different things. If, for instance, we examine the cambium in 

 the earliest period at which it begins to acquire organisation, 



1 This position has undergone essential modifications, in consequence of subsequent 

 researches which I have made with respect to the cambium, and which proved thai 

 a cambium, in the sense in which it had been previouslj used in physiology, nan 

 as denoting an amorphous formative fluid between the \\<><mI and bark, had no « I 

 enceatall; that the wood and the bark, on thi form one uninterrupted 



continuity, and their margin i* merelj denoted bj a Layei <»f di ly-walled, gela- 

 tinous cellular tissue. 



