256 
The Ohio Naturalist. 
[Vol. VIII, No. 4, 
lower end of the Angiosperm embryosac is the morphological 
equivalent of the upper, the lower polar being thus also homol¬ 
ogous to a ventral canal cell. In other words, the typical 
embryosac or female gametophyte of the Angiosperms, with its 
symmetrical arrangement of four cells at opposite poles, repre¬ 
sents two archegonia, the vegetative cells having disappeared. 
There is much in favor of this theory from the standpoint of 
the writer. In 1896, in my paper on Alisma plantago, 3 I made 
the statement that “Especially in regard to the real meaning of 
the conjugation of the polar nuclei, and what is represented by 
the antipodal cells, does there still seem to be much obscurity.” 
But my study of the Angiosperm embryosac gave no light on 
these two important questions except that I observed the fol¬ 
lowing facts: “The cells in the antipodal region simulate the 
arrangement in the egg-apparatus. There are two small nuclei 
lying at the base; and beyond them is the third antipodal 
nucleus.” “It would by its peculiar appearance suggest that it 
may be the homologue of the oosphere.” (Italics not in the 
original.) 
Chamberlain 4 had, in 1895, figured and described what he 
felt positive was a veritable oosphere in the antipodal region of 
Aster. It would appear that the extensive antipodal region of 
Aster still has the ability to develop a structure very similar in 
appearance to the micropylar egg apparatus. Chamberlain, how¬ 
ever, did not take advantage of his remarkable discovery to 
assert the similar nature of the two ends of the sac, being prob¬ 
ably hindered from doing so by a too strict adherence to the 
prevailing hypothesis that the antipodal region represents the 
vegetative thallus of the Angiosperm female gametophyte. 
If Porsch’s view of the homologies is correct, it becomes evi¬ 
dent that we have, as he ably shows, an easy explanation of the 
origin and nature of the triple fusion process, or what has 
improperly, to my mind, been called double fertilization, which 
appears to be so common in the Angiosperm sac. 
I wish to add an explanation of certain peculiarities not 
specially touched upon by Porsch. In my paper on Sagittaria 
latifolia 5 I made the following observations: “ approaching 
each other the upper larger polar nucleus travels much farther 
than the lower one, so that the place of contact is usually in the 
lower part of the embryo sac, and the fusion takes place here 
without any apparent shifting of the nuclei, the fusion being 
usually complete before the entrance of the pollen tube into the sac.” 
3 Schaffner, John H. The Embryosac of Alisma Plantago. Bot. Gaz. 21 : 123-132. 
4 Chamberlain, Chas. J. The embryo-sac of Aster Novae-Angliae. Bot. Gaz. 
20 : 205-212. 
5 Schaffner, John H. Contribution to the Life History of Sagitaria variabilis. 
Bot. Gaz. 23 : 252-273, 1897. 
