ORGANS AND SYSTEMS OF OBGANS. 167 



D. METAMORPHOSIS AND CORRELATION. , 



It is highly essential that every one who devotes his attention 

 to the different tendencies of our science should adhere to the 

 purely botanical definition of metamorphosis. It would of course 

 be a waste of time and energy to try to disprove such a thing as the 

 occurrence of metamorphosis ; however, it is necessary to dispel the 

 erroneous conception that in metamorphosis there is a real trans- 

 formation of one organ into another. Although we cannot follow 

 the eminent morphologist GOBEL in his explanation of organ meta- 

 morphosis l (I have stated my objections in Natur und Offenbar- 

 ung, 1893), yet I agree with the author in his introductory state- 

 ments that (1) there is a wide difference between true metamor- 

 phosis and the metamorphosis of GOETHE and A. BRADN, and (2) in 

 not a single instance have we been able to prove the phylogenetic 

 origin of any leaf-formation due to real transformation. An impor- 

 tant statement from so eminent an authority. 



Cotyledons, cataphyllary leaves, foliage-leaves, and floral leaves 

 show such great similarity in their early stages of development that 

 one might well speak of them as the beginnings of members of the 

 same morphological value. They are simply more or less extended 

 cellular protuberances or warts upon lateral portions of the stem. 

 However, in their subsequent development they are transformed 

 into organs having widely different functions. Even what was 

 originally the beginning of a leaf may not always develop into a 

 leaf: it may develop into a prickle, tendril, or suctorial foot organs 

 which are no longer called leaves. Such a change in development 

 is known in the vegetable kingdom as metamorphosis. 



Based upon the above statements we may accept the follow- 

 ing definition as given by SACHS in the year 1868 : 2 Metamorphosis 

 is the varied development of members of the same morphological 

 value for the purpose of adapting them to definite functions. 



One might incline to the view that since metamorphosis is 

 identical with the normal development of the organs it is unneces- 

 sary to speak of them as " transformations." It must, however, be 

 observed that the term metamorphosis implies that the originally 



1 Beitrage zur Morphologie und Physiologic des Blaltes, Botanische Zeitung, 

 1880. 



2 Lehrbuch der Botanik ; Vines' translation of the edition of 1874. 



