OOGENESIS IN PINUS 271 
In later stages it may be difficult to identify the ventral canal 
cell as a whole, but vestiges of it in one form or another can 
usually be found up to the time when the pollen tube enters 
the neck of the archegonium, and occasionally traces may 
be seen even after the sporophyte is considerably advanced 
(fig. 194. v.). 
While the above account gives the usual history of the ven- 
tral canal cell, there are other rather exceptional cases which 
belong to an opposite course of development and are interesting 
oi account of their bearing upon the homology of the ventral 
famal cell. Fig. 7, which is drawn to the same scale as fig. 2, 
‘hows an enormous spindle, somewhat loosely attached to the 
daughter nuclei. This ventral canal cell is eight or ten times as 
ge as the typical one shown in fig. 2. It contains several pro- 
we vacuoles like those of the oosphere, and its nucleus is under- 
aoe usual-developmental changes which will be described 
Sr the nucleus of the oosphere. In this particular case, the 
ss a the oosphere and ventral canal cell’are of nearly the 
“a and are in the same stage of development. Ifa pollen 
a * on enter, it seems reasonable to suppose that fertiliza- 
4 course aha canal cell might result. A later stage in such 
Aucleus . development is represented in fig. 70, in which the 
Oosphere sa almost reached the condition presented by an 
are in ab nucleus just before conjugation. In fig. & the nuclei 
Ventral . Same stage as in fig. 7, but the wall between the 
th es; = and the oosphere has broken down, leaving 
Spindle are ai in the oosphere. Fragments of the 6 pe 
a Strong nate throughout the oosphere. In snme of t oe 
Sare dra die a part of the cell plate a Bet 
A similar Sip teas wre resembling tips of bipolar spin = : 
"ached the 41s shown in fig. 9, but here the nuclei have ne : y 
Still another size and Stage of development shown in - fe 
710, the “ae is shown in outline in fig. 794, ?: ne 
Nore favorab] » se the ventral canal eel, on ann ne 
tion than the © position, would be more likely to secure tertt’ . 
more remote nucleus of the oosphere. One mig 
