28 



ON SEEDLINGS 



on the ventral surface. The embryo (fig. 60, r, c) is curved, 

 following the concavity of the hollow, with the larger part of 

 the endosperm lying towards the periphery. The cotyledons 

 are linear and obtuse. Fig. 60 shows that, so far as the form 

 of the seed is concerned, there is no reason why the cotyledons 

 should not be much broader than they are. The explanation 



FIG. 59,-Coreopsis auriculata. A, achene, x 14. B, longitudinal section, x 14 

 C, transverse section, x 14. D, embryo, x 14 



may perhaps be found in the structure of the pericarp (fig. 60, 

 p.c), which is thick, tough, and corky. It is very impervious 

 to water, and may be advantageous to the embryo by resisting 

 the attacks of drought and of insects, and perhaps if the seed 

 be swallowed by a bird, by protecting it from being digested. 

 On the other hand it does not split open, and is too tough to 

 be torn by the embryo. The cotyledons, therefore, if they 



