TILIA 55 



very dissimilar in form to that of the Lime (Tilia) ; and yet 

 the cotyledons are long, narrow, and strap-shaped, while those 

 of the Lime are rhomboid and five-lohed ; but it must be 

 remembered that in the Sycamore the embryo occupies the 

 whole seed, while in the Lime it is embedded in endosperm. 



The peculiar lobed form of the cotyledons of Tilia thus 

 enables them, I would suggest, to lie conveniently in the 

 globose seed. 



AURICLED COTYLEDONS. 



Some cotyledons are markedly auricled. As illustrations 

 I give Poterium (fig. 42) and Hakea (fig. 21). This form is, I 

 am disposed to suggest, a provision to fill up vacant space in 

 the seed. In the seed of Hippophae (fig. 53) the form of the 

 cotyledon leaves at each side of its base two spaces (d), which 

 are occupied by endosperm. In Cuphea (fig. 84), Euellia (fig. 

 55), and Poterium (fig. 83), on the other hand, there is no 

 endosperm, and it is consequently an advantage that the 

 cotyledon should develop auricles in order to fill up the 

 space. 



If this is the explanation of the auricles, we should expect 

 to find them developed principally in families where the endo- 

 sperm is deficient. Now 

 in the species I have ex- 

 amined, auricled cotyle- 

 dons occur in 35 genera, 

 belonging to 22 families, 

 of which 13 have no 

 endosperm, while in 6 of 

 the 9 others it is reduced 

 almost to a film. 



The argument in the 



F n , f ,1 FIG. 103. Three stages in the growth of 



Case Of Cuphea IS further the see aimg of Cuphea attenoides. 



strengthened by the pecu- 

 liar conformation of the radicle (fig. 84), which is three- 

 lobed, the reason being, I would suggest, that the radicle co- 

 operates with the cotyledons in the endeavour to fill up the 

 vacant spaces. 



In support of this view I also would observe that the 



