DIFFERENCES IN ALLIED SPECIES 



29 



had widened, as they might otherwise have done, would have 

 found it impossible to emerge from the seed. They evade the 

 difficulty, however, by remaining narrow (fig. 60, C). On the 



FIG. 60. Galium saccharatum. 

 A, longitudinal section of seed, 

 x 8. B, transverse section of 

 seed, x 8. C, germinating seed- 

 ling, x4. 



PIG. 61. Galium Aparine. A, 

 longitudinal section of seed, 

 x 8. B, transverse section of 

 seed, x 8. C, germinating seed- 

 ling, x4. 



other hand, in G. Aparine the pericarp is much thinner (fig. 61), 

 and the embryo is able to tear it open (fig. 61, C). In this case, 

 therefore, the cotyledons can safely widen without endangering 

 their exit from the seed. 



