402 



PART IV. CLASSIFICATION. 



The embryo-cell divides, as a rule, into two by a longitudinal wall, 

 then transversely, and then in a plane perpendicular to both the 

 preceding, into octants ; but while the four anterior octants are 

 octants of a sphere, this is not the case with the four truncated pos- 



FIG. 239. Embryogeny of Dicotyledons as represented by Capsella Bursa~Pastori$ (dia- 

 grammatic, after Goebel and Hanscein). A-D Successive stages: susp. suspensor; einb. 

 embryo; 1-1, 2-2, octant-walls ; a lowest cell of suspenscr, dividing in B to form the hypo- 

 pbysial cell h ; in C the hypopbysial cell has divided into two, h, and h,, the former con- 

 Btituting the periblem, the latter the dermatogen, of the growing-point of the primary 

 root ; in D, h, has undergone a periclinal division to form the primitive root-cap : d derina- 

 togen ; c periblem ; pi. plerome ; cot. cotyledons, between which lies the growing-point of 

 the primary stem. 



