94 BOTANICAL GAZETTE [Avcust © 
alk stages are found, to the one just preceding the elimination of | 
archegonia; and this stage is attained by Tumboa and Gnetum. 
The general tendency of the archegonia among gymnosperms is 
to eliminate the ventral canal cell. The gymnosperms are distin- 
guished from the pteridophytes by the complete elimination of neck 
canal cells, and this tendency to suppress all of the axial row except 
the egg continues among gymnosperms. Among the living forms, | 
present among the ancient gymnosperms. In the other living 
groups the wall has disappeared, and the ventral canal cell is repre- 
sented by a free nucleus. In certain forms even this nucleus may 
have disappeared; and of course there is no trace of it when t 
archegonia are eliminated. 
The distribution of archegonia may be considered in this connec 
tion, although the tendencies do not appear general. It is becoming 
evident that the position of archegonia is related to the position of the 
pollen tube, which often reaches the embryo sac before the arche- 
gonium initials are selected. In cases where the pollen tube assumes 
a lateral position in reference to the gametophyte (as in Sequoia and 
Widdringtonia), it has been demonstrated that the latter responds 
by the selection of numerous deep-seated and laterally placed arche- 
gonium initials. It may be inferred, therefore, that the usual micro- 
pylar position of archegonia is due to the usual micropylar position 
of the tip of the pollen tube. It may be that numerous scattered and 
sections of Paleozoic ovules that reveal archegonia, and also the 
archegonia of heterosporous pteridophytes, suggest the opposite ¢ 
clusion. In any event, they tend to become definite in number and 
are then organized in two ways: either as individual archegoni . 
each with its own jacket and chamber; or as an archegonial complex, 
with a common jacket and chamber. The latter may seem tO 
a specialized condition, exhibited chiefly by Cupressineae, but ™ 
also seems to be the natural condition from which to derive the free 
eggs of Tumboa and Gnetum when archegonia are eliminated 
ontogeny. 
