334 BOTANICAL GAZETTE [May 
prominent, however, and the embryo sac while smaller is more 
densely filled with protoplasm (jig. 72). 
CONCLUSIONS. 
I had hoped by a comparative study of closely related 
monocotyledons, and also of related dicotyledons, to be able in 
some degree at least to show how far the characters of the 
gametophyte generation could serve the purpose of indicat- 
ing relationships among the larger groups of angiosperms. In 
this hope I have been disappointed. Those characters of the 
gametophyte generation in which, for example, Pontederia and 
Eichhornia agree, are characters which are common to hundreds 
of species of widely separated orders. The origin of the 
sporogenous tissue from the hypodermal cell terminating aa 
axial row, the well-nigh universal occurrence of four megaspore 
mother cells of which but one matures, the usual cutting-off of 
a tapetal region which is finally absorbed by the growing mega 
spore, the division of the megaspore nucleus into eight ue 
nuclei which are arranged in two groups of four each, the fusion 
of the polar nuclei to form a definitive nucleus which is the mother 
nucleus of the endosperm —these are the gametophytic characters 
of angiosperms in general. As soon asthe comparison is pushed 
further we see that the differences between the two knee ” 
respect of the gametophyte are quite as great as often in other 
cases between unrelated plants, and the most striking ee 
such as the shape of the ovule, embryo sac, and inte ee 
really sporophyte characters. If we were to draw up atabu 
statement of the points in question in whic i 
Pontederia agree, it would consist of two items: ie 
nature of the antipodals, which, however, is a chara pa 
most monocotyledons; and the structure of the ve been 90 
Probably the female gametophyte of angiosperms of features 
long parasitic upon the sporophyte that its only constat : 
are those of overwhelming phylogenetic ad a ee specific 
minor characters are readily variable in adaptation to the 
or generic differences of the sporophyte, oF per 
od ats ie FA ea i 
