2 56 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,^ 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 stiU 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 oospJiere." (Italics not in the 

 original.) 



Chamberlain^ 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- 

 ablv 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 W3 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 fertihzation, which 

 appears to be so common in the Angiosperm sac. 



I wish to add an explanation of certain pecuharities not 

 specially touched upon by Porsch. In my paper on Sagittaria 

 latifolia'^ I made the following observations: " approaching 

 each other ths 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, tlie fusi:n being 

 usually complete before the entrance of the pollen tube into the sac." 



3 ScHAFFNER, JoiiN IT. The Embryosac of Alisma Plantago. But. Gaz. 21 : 12.'3 -132. 



4 Chamberlain, Chas. J. The embrvo-sac of Aster Novac-Angliae. Bot. Gaz. 

 20 ; 205-212. 



.") ScHAFFNER, Joiix H. Contribution tn the Life HiUorv of Sanitaria variabilis. 

 Bot. Gaz. 23 : 2.'i2 -273, 1897. 



