SIR J. LUEBOCK rnXTOBIOLOGICAL OBSERYATlOyS. 



399 



them down again on themselves (fig. 133, ). This growth is con- 



tinued until the tips reach the radicle again, and ihe 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. 133, s) against the process which encloses the radicle. 



1 



Fig. 133, 



a 



3 



4 



5 



€ 



7 



Acer Pseudo-Flatamis, 

 ^ Sections of seed in seven successive stages, showing growth of embrjo. X 3. 



then their general direction naturally carries them outwards, 

 until the wall of the seed again turns them upvvards, so that 

 they become plicate ; if, on the contrary, the tips of the coty- 

 ledons pass just within the micropylar process and touch the 

 radicle, then they are compelled to grow in the opposite direction, 

 and they become spirally coiled. In the specimens examined the 

 latter arrangement was exceptional. 



Forms of the First Leaves. 



Time does not permit me to enter into any particulars with 

 reference to the first leaves and the transition between them and 

 those of the final form. I will only observe that the fir.st leaves 

 are generally simple, or at any rate simpler than those w*hich 

 folio 



In species with trifoliate leares, the first leaf is generally 

 simple, as in the Clovers. AVhen the mature leaves are j)innate, 

 the first ones are generally trifoliate; and when the final leaves 

 are bipinnate, the first ones are generally pinnate. I have already 

 observed that species w ith lobed or palmate leaves often commence 

 with one or more which are entire and heart-shaped. 



w. 



