1 14 Campbell . — The Embryo-Sac of Peperomia. 
there may not be some points in their structure which might 
be compared with some of the stages of development in 
Peperomia. That Saururus 1 should show a typical angio- 
spermous embryo-sac is to be expected, as it does not exhibit 
any especially primitive features in the flowers, and is 
distinctly more specialized in this respect than are the 
Piperaceae. 
As regards the significance of the fusion of the endosperm- 
nuclei, we agree with Johnson and Strasburger 2 that it is 
not a true fertilization, but has a nutritive significance only ; 
and the whole endosperm, as well as the antipodal cells or 
their equivalents, represent gametophytic structures, and the 
endosperm is not to be considered as an embryo. 
The behaviour of the endosperm-nuclei in Peperomia is 
a strong argument in favour of its primitive character, and 
is what might be expected from its other peculiarities. In 
harmony with the generalized character of the other structures 
of the embryo-sac, there occurs, instead of the two definite 
polar-nuclei of the other Angiosperms, a fusion of a somewhat 
variable number, which cannot be seen to bear any definite 
relation to a#y of the primary nuclei of the sac. With the 
reduction by half in the number of the embryo-sac nuclei, 
and the strongly marked polarity observed in most Angio- 
sperms, the number of these nuclei becomes reduced to two, 
the polar nuclei, and the antipodal cells assume their charac- 
teristic position. 
In regard to the homologies of the structures in the 
embryo-sac, the writer believes that the contents of the 
embryo-sac with the sixteen nuclei represent a prothallial 
tissue, and the nuclei are at first entirely similar. One of 
these becomes differentiated to form an archegonium, which 
is reduced to a single cell — the egg-cell. Whether the 
adjacent nuclei are to be considered as synergidal nuclei 
1 Johnson, D. S., On the Development of Saururus cernuus , L., Bull, of the 
TorreyBot. Club, July 27, 1900. 
2 Einige Bemerkungen zur Frage nach der 1 doppelten Befruchtung ’ bei den 
Angiospermen. Bot. Zeit., 1900, p. 293. 
