94 SCIENCE PROGRESS. 



are merely phyllomes which are differentiated, having 

 assumed different forms in relation to their diverse func- 

 tions : but stamens are by no means metamorphosed foliage- 

 leaves. Stamens and foliage-leaves are only equivalent, as 

 regards their relation to the entire shoot, to the axis which 

 bears them." And again Hanstein, 1 in one of his last 

 memoirs, writes: "Further, the fact that all these various 

 forms of leaves succeed each other from below upwards on 

 the shoot, and are, at the same time, frequently connected 

 by intermediate forms so that the primitive identity of their 

 morphological nature is more clearly brought to light, re- 

 veals them as modifications of one and the same organic 

 type which successively transforms itself into each of these 

 organs. This process, which is rather theoretical than 

 actual, is what is termed the Metamorphosis of the leaf." 



On the other hand Schleiden, 2 faithful to the traditions 

 of Wolff, stoutly maintains the view of material meta- 

 morphosis. Beginning with the blunt statement that 

 " Science, to her great detriment, received this thought 

 (metamorphosis) not from Wolff but from Goethe, a thought 

 which might have proved so fruitful, but which, owing to 

 the manner in which Goethe introduced it, has been of 

 relatively so little use," Schleiden goes on to give his con- 

 ception of metamorphosis as "the fact that the plant 

 possesses but few essentially different organs, and that all 

 the others differ only dynamically from these fundamental 

 organs in that there is inherent in them a tendency to 

 undergo a definite and characteristic development and 

 modification ; a tendency which is, however, not so absolute 

 but that it can be overcome under special circumstances, 

 and then the normal form of the organ again becomes 

 apparent ". The language of this confession of faith is some- 

 what involved, but its purport is unmistakable. 



There can no longer be any doubt that the weight of 



1 Hanstein, " Beitr. zur allgemeinen Morphologie der Pflanzen," Bot. 

 AbhandL, iv., 1882, p. 30. 



' l Schleiden, " Einige Blicke auf die Entwickelungs-geschichte des 

 vegetabilischen Organism us bei den Phanerogamen ; " in his Beitrage zur 

 Botatiik, 1844, p. 86. 



