CONIFERALES (TAXACEAE) 33^ 



jacket of the mother cell and early embryo sac ("spongy tissue") 

 in the same group. The conspicuous archegonial jacket of Phyl- 

 lodadus suggests that this structure may be as fully developed among 

 podocarps as among Pinaceae. A peculiar situation is developed in 

 Phyllocladus (174) in the relation of the neck cells to the jacket cells. 

 It had been observed (144) that the top of the archegonium is its 

 widest part, the whole outline being roughly funnel-shaped, resulting in 

 leaving the neck cells apparently detached. This is found to be due 

 to the rapid centrifugal growth of the adjacent tissues at the upper 

 end of the endosperm, but the neck cells remain anchored to the 

 jacket cells by a membrane. 



In all the Taxaceae observed no ventral canal cell is formed, but a 

 ventral nucleus is cut off by the central cell, which is more or less 

 ephemeral. Attention has been called to the fact (p. 268) that this is 

 a stage toward the elimination of the ventral canal cell, and it has 

 been reached by all the conifers except the Abietineae and possibly 

 the Araucarineae. The Taxaceae in which a ventral nucleus has been 

 definitely observed are Taxus, Cephalotaxus (124, 130), Phyllocladus 

 (174), Podocarpus (69), and a somewhat doubtful case in Torreya 

 (99). The case of Torreya calif ornica was an inference from a 

 spindle seen twice in the central cell, and it is not always easy to 

 distinguish a central cell from an egg. In Torreya taxifolia (loi) 

 the series seemed to be close enough to detect a ventral nucleus if 

 one was formed, but no trace was found, the nucleus of the central 

 cell appearing like an egg nucleus from the very beginning. It is 

 very unsafe to infer the absence of a ventral nucleus from a single 

 investigation, but it is so very ephemeral in some cases that it may 

 have disappeared entirely in other forms. So far as any general 

 conclusion is safe, it may be said that among the Taxaceae the cen- 

 tral cell does not cut off a ventral canal cell, but that a ventral nucleus 

 appears which is sometimes very ephemeral, and that in some cases 

 even the nucleus may not be formed. In Cephalotaxus drupacea 

 (130) the ventral nucleus is so ephemeral that it degenerates before 

 fertilization; while in Podocarpus (69) it has been observed to divide 

 amitotically after fertihzation. 



Among the Podocarpineae the number of archegonia ranges from 

 one to eleven, being one to four in Phyllocladus alpina (144), and 



