74 ON SEEDLINGS 



oblong-lanceolate (fig. 118, 2). When the cotyledons have 

 reached the upper, narrow end of the seed, the curvature of 

 the wall turns them down again on themselves (fig. 118, 3). 

 This growth is continued until the tips reach the radicle again, 

 and the ultimate arrangement of the embryo differs according 

 to whether they then curve inwards or outwards. This, again, 

 seems to depend on the exact direction of the growth of the 

 cotyledons. If they strike (fig. 118, o) against the process 

 which encloses the radicle, then their general direction natu- 

 rally carries them outwards, until the wall of the seed again 

 turns them upwards, so that they become plicate ; if, on the 

 contrary, the tips of the cotyledons pass just within the 



FIG. 118. Acer Pseudo-Platanus. Sections of seed in seven successive 

 stages, showing growth of embryo, x 3. 



micropylar process and touch the radicle, then they are com- 

 pelled to grow in the opposite direction, and they become 

 spirally coiled. In the specimens examined the latter arrange- 

 ment was exceptional. 



FORMS OF THE FIRST LEAVES. 



Some particulars with reference to the first leaves and the 

 transition between them and those of the final form will be 

 found in the following pages. I will only here observe that 

 the first leaves are generally simple, or at any rate simpler 

 than those which follow. 



In species with trifoliate leaves, the first leaf is generally 



