28o BOTANICAL GAZETTE [October 



(fig 



(fig 



(figs 



integrates {fig. ig). The suspensor quickly elongates, thrusts the 

 embryo initial deeply downward into the gametophyte, and remains 

 turgid until the secondary suspensor appears (fig. 2j)y when it col- 

 lapses. The longest suspensor noted reached a length of 3.1 



mm 



immediately before the differentiation of dermato 



^-r 



is cut off early, as shown by fig. 2j. The latter figure also shows the 

 first appearance of the secondary suspensor, a later stage of which is 

 shown in fig. 24. The secondary suspensor is added to by successive 



mer 



from 



and lastly the 



ondary suspensor (''le columelle'' of Jaccard), derived from the 

 sal cells of the embr}"0. 



Coincident with fertilization and development of the proembryos, 



I 



large, two smaller, and one very minute, were observed in a proem- 



bryonal cell. The suspensor tube is immediately directed downward 



toward the antipodal region if the cell is the lowest one in the arche- 



gonium, but outward and then downward if from one of the upper 



cells. Fig. 13 shows the suspensor tube before either of the nuclei i 



has entered it. The larger nucleus passes down nearly to the end 



of the suspensor tube, and immediately behind it a cleavage ring, 



beginning at the wall of the suspensor tube and gradually extending * 



j 



inward, appears in the cytoplasm and separates it into two masses, ! 



each containing a nucleus. Fig. 14 shows the cleavage ring incom- 

 plete; and fig. 75 is a much higher magnification of the same section. i 

 A wall separating the suspensor tube into two regions is then estab- 

 lished at the cleavage plane. 



! 



The nucleus of the embryo initial cell divides and a transverse wall 

 is laid down in the usual way along the cell plate {fig. 18). Fig. 19 

 shows a two-celled embryo with the wall fully established. An anti- 

 clinal division of the basal cell next occurs, the wall being either 

 parallel with the suspensor {fig. 21) or slightly inclined {fig. 20). {I 



.! 



i 



1 



into the root cap. There are three stages of suspensor formation: 



the suspensor tube, initiated by the activity of the nucleus which 1 



finally becomes the embryo-initial nucleus; the single suspensor, 



i 



