72 postelsta 



of the primordia. The influence of 

 their ultimate positions has been carried 

 back so far in the embryogeny of the 

 ferns, which very early become inde- 

 pendent, that there has evidently been 

 a displacement of the primordia within 

 the oosperm itself, for the root primor- 

 dium arises from a hypobasal octant 

 diametrically opposite the stem primor- 

 dium, and the foot arises as a lateral 

 organ from two other hypobasal octants. 

 In the embryogeny of the sporo- 

 phyte the Monocotyledons as a class 

 show considerable diversity. The 

 greater number of investigated types 

 conform more or less closely to a 

 definite scheme, of which the em- 

 bryogeny of Alisma affords a good 

 example. The oosperm first di- 

 vides by a basal wall at right angles 

 to the longer axis of the embryo-sac. 

 The hypobasal cell (next the micro- 



