1914] MANEVAL—MAGNOLIACEAE II 
nuclei by one division; that of Lilium as the product of all of these 
nuclei by one division; and that of Peperomia from all of these 
nuclei by two divisions. The three latter cases clearly show an 
abbreviation in the course of development of the gametophyte, 
whether we regard that course as beginning with the embryo sac 
mother cell or after chromosome reduction. 
That we cannot make chromosome behavior the sole criterion 
for distinguishing sporophyte and gametophyte is doubtless true. 
This is evident from chromosome behavior in cases of partheno- 
genesis such as occur in Alchemilla (19), and in the numerous 
instances of apogamy and apospory among both pteridophytes 
and spermatophytes. However, it is probable that no one has 
ever dreamed of making such unusual phenomena the basis of any 
theory of the nature or phylogeny of the angiospermous embryo 
sac. These phenomena undoubtedly are secondary. Hence the 
conception that chromosome behavior is the most important 
criterion, at least in all cases where fertilization occurs, seems well 
founded. So if abbreviation in the developmental history of the 
gametophyte in angiosperms expresses an evolutionary tendency 
which can be traced back as far as the gametophyte of the pterido- 
phytes, then anomalous embryo sacs are secondary rather than 
primitive types. 
If now the embryo sacs of those Magnoliaceae thus far investi- 
gated are considered, no clue is discovered in their development or 
structure as to the primitiveness of the group; and this for the 
simple reason that, although we regard this type as the most 
primitive among angiosperms, yet the same type is the common 
one among all angiosperms. Moreover, whatever theory we accept, 
the past study of the embryo sac has served mainly to emphasize 
the vast difference between angiosperms and lower groups of plants 
in this respect, and so to increase rather than to bridge the wide 
gap between them. It would seem then that if the problem of the 
origin of angiosperms is to be solved this must come about princi- 
pally as a result of investigations of other features than the embryo 
sac. 
During the last two decades the amount of purely descriptive 
literature dealing with embryo sacs has grown to huge proportions, 
