169 



all other Archegoniates that have been critically examined. It 

 is more likely that its absence in most of the archegonia is 

 due to the fact that it is formed very late, and is extremely 

 inconspicuous. The same apparent absence of a ventral canal 

 cell in the Cycads and some Conifers has been shown, on more 

 critical study of the material, to be due to the small size ot 

 the ventral nucleus and its very evanescent character. In one 

 case (Fig. 110) there seemed no doubt about the presence ot 

 this cell, and in nearly all the archegonia examined just before 

 they opened there was present a vesicular body above the egg, 

 and this was probably the ventral canal cell much distended 

 with fluid preparatory to the opening of the archegonium. A 

 small nucleus, or what looked like one, could be seen in a 

 few cases, but it must be said that its nuclear nature was 

 not above suspicion (Figs. lOS, 111). 



Just before the archegonium is ready to open, the egg-cell, 

 which, up to this time, is compressed above by the basal wall 

 of the neck canal cell, becomes rounded and pushes up the 

 base of the caual cell, which becomes convex upward. It is 

 about this period that the ventral canal cell is cut off. It 

 appears (Fig. 110) as a very narrow cell in which the nucleus 

 can be only imperfectly m.ade out, as it seems to be extremely 

 compressed and is very much smaller than the nucleus of the 

 egg. Unfortunately no cases were found showing the mitosis 

 in the central cell, but there seemed no reason to doubt that 

 this narrow cell is really the ventral canal cell. Very soon 

 this cell becomes much enlarged, and appears almost trans- 

 parent, owing to its scanty contents (Fig. 108). 



The neck canal cell does not show the complete disorgani- 

 sation which is common, but retains its form up to time the 

 archegonium opens. With the opening of the neck there is 

 some elongation of the outer neck cells, but there is decidedly 

 less projection about the surface of the prothallium than is 

 the case in 0. vulgatum.. The nucleus of the egg-cell is large, 

 but it does not always stain readily except for the nucleoli, 

 and it may be that the same resistence to stains is the 



Ann. Jard. bot Buitenz. 2e Ser. Vol. VI. 12 



