i6o 
WALTER P. THOMPSON 
found and in which no polarity is evident. Many such sacs have 
been described in recent years and it is by no means proven that they 
are speciaHzed and not primitive as was originally contended by 
Campbell but disputed by Johnson. When the development of the 
endosperm is described (page 34) it will be seen that there is a still 
further resemblance. It seems particularly significant that Peperomia 
should also resemble Gnetum in many points of flower structure and 
that it should be classified by universal consent among the very lowest 
of the Angiosperms. 
Whether or not the female gametophyte of Gnetum represents 
the condition from which the Angiosperm gametophyte was really 
derived, it seems to have a bearing on the morphological nature of 
the cells within the Angiosperm embryo-sac. Many attempts have 
been made to relate the egg and synergids to the archegonium of 
lower plants. It has been urged at different times (i) that they 
represent the egg and canal cells of a single archegonium, (2) that all 
three represent archegonia, and (3) that only the egg represents an 
archegonium while the synergids represent the upper part of the 
prothallus (Berridge and Sanday 4). The conditions in Gnetum show 
that there is no need to relate the eggs in any way to archegonia but 
merely to consider them as eggs produced by a gametophyte which 
cannot form archegonia. The absence of cellular tissue prevents the 
formation of archegonia and hence free nuclei organize as eggs. If 
this is true for Gnetum it is still more evidently true for Angiosperms 
even though there be no genetic connection between them. 
The conditions in the female gametophyte may be summarized 
as follows: the whole sac is shaped like an inverted flask; at the mouth 
of the flask is a considerable mass of cytoplasm and free nuclei ; along 
the sides of the neck a narrow band of cytoplasm with one row of 
nuclei; in the body a broader band of cytoplasm with one or more 
rows of nuclei; in variable positions one or more eggs. The inferences 
to be drawn from these conditions are: (i) The early development 
is Gymnospermic, (2) the later development and mature condition is 
even more suggestive of Angiosperms, particularly of the irregular 
forms, than had been supposed, (3) it is impossible to relate any 
structures in this or the Angiosperm gametophyte with the archegonia 
of lower forms. 
