12 



-MORPHOLOGY 



After this is consumed and in good part converted into struc- 

 ture, the plantlet must l>y the action ol' its root and leaves imbibe 

 from the soil and air appropriate materials, and 

 assimilate them into nourishing matter needful 

 for further growth. Only then does the rudi- 

 ment of new structure appear, in the form of a 

 growing point, or bud. at the node or apex of 

 the primitive stemlet. between the two seed- 

 leaves. In this case it soon .shows itself as 

 a second pair of leaves, at first resting on 

 the node (Fig. 'J). next as somewhat upraised 

 by the development of the second intcrnocle 

 (Fig. 10, summit), and finally both this inter- 

 nodi 1 and the pair of leaves complete their 

 growth (Fig. 11). Then the terminal bud 

 which crowns the second node develops in 

 the same way the third pair of leaves and 

 their supporting inteniode or joint of stem 

 (Fig. 12) ; and so on. 



24. The root and the stem grow not only 

 in opposite directions, but in a different mode. 

 The primordial stem, pre-existing in the seed 

 (though at first it may be extremely short) 

 grows throughout its whole length, but most 

 in its upper part, so that it may become a 

 stemlet two or three inches long. l>ut. soon 

 attaining its full growth as to length, the 

 stem is carried upwards by the subsequent joints or portions, 

 similarly developed and elongated, one after the other. Not 

 that each portion necessarily waits until the growth of its prede- 

 cessor is complete, though this occurs at first in seedling Maples 

 and other embryos unprovided with much store of food, yet the 

 development follows this course and order of succession. The 

 root, on the contrary, cannot be said to pre-exist in the seed, or 

 at most it may be said to exist potentially in tissue of the caulicle 

 from which a root or roots normally originate. 1 It is formed 



1 Vet from nothing which is special to this part of tin- embryo, nor to the 

 embryo at all. The primary root is developed from subjacent tissue of the 

 tip of the eauliele. just MS it is sometimes developed from ahmu the sides, 

 and as secondary roots are from all or must Mems under favoring conditions. 

 This complete similarity, and the fact of \vhat is called the "endogenous" 



origin of roots (i.e. their sprinirinir from subjacent rather than superficial 



tissue) appear fully to warrant the statement in the text above. 



Fit!. 10. Mapli 1 plantlet with scniml internode developing. 1). Same with second 

 nair of li>;ivr- rimijili-ti 1 . anil bud of the third apjiavrnt. 



