60 MORPHOLOGY. 



2. What we are to understand by Vegetable Meta- 

 morphosis, or Morphology, is " that every appendage 

 of the axis is originally constructed of the same ele- 

 ments arranged upon a common plan, and varying in 

 their manner of development, not on account of any 

 original difference in structure, but on account of espe- 

 cial, local, and predisposing causes ; of this the leaf is 

 taken as a type, because it is the organ which is most 

 usually the result of the development of those elements 

 is that to which other organs generally revert when 

 from any accidental disturbing cause they do not sus- 

 tain the appearance to which they were originally pre- 

 disposed and, moreover, is that in which we have the 



most complete type of organisation." 1 " We cannot 



say that an organ is a metamorphosed leaf, when in 

 point of fact it has never been a leaf." (Dr. Lindley.) 

 Therefore when the term metamorphosis of leaf is made 

 use of in the following paragraphs, the student can 

 apply to it its intended signification. 



3. Of the theories of the general principles of Mor- 

 phology, there are several the results of the labours 

 chiefly of the German Botanist ; and from that of Von 

 Martius we shall extract the few remarks that follow' 

 these observations, and say a few words at the close of 

 them upon certain parts of structure, and the symmetrical 

 development of form. 



a. A plant grows upwards and downwards, and so 

 complete are the differences between these modes of 

 growth, that in their consequences are included forma- 

 tions of very different nature to each other. 



b. The root, shut up in itself as it were, is that, truly 

 simple and uniform in a plant, unchangeably conti- 

 nuing its direction below, and extending itself out by 

 division, but being neither in the whole or individual 

 parts an active formation. 



c. The upward growth of a plant is the light and 

 air system of the same, and is directly opposed to that 

 of the root. 



