CYCADALES i49 



geria paradoxa (90) . In these five forms the entire sperm enters the 

 egg, but the nucleus soon shps out from the cytoplasmic sheath, and 

 moves toward the egg nucleus. The ciliated band was observed 



Fig. 176. — Dioon edule: upper part of ovule at time of fertilization, showing 

 integument, nucellus, and both male and female gametophytes; reconstructed from 

 sections of several ovules. — After Chambeel.4IN (73). 



by Lang (29) in the upper part of the egg of Stangeria, which 

 later proved to be an exceptionally favorable form for the study 

 of spermatogenesis, fertihzation, and embryogeny (90). The 

 sperm nucleus is much smaller than that of the egg, and it 

 penetrates some distance into the egg nucleus before the bound- 



