No. 430.] THE EMBRYO SAC OF ANGIOSPERMS. 781 
was confirmed by Johnson,! who also discovered that the endo- 
sperm nucleus was the product of the fusion of several nuclei, 
instead of two, as in the typical angiosperms. In Peperomia 
there is no clearly defined egg apparatus, nor are there any 
proper antipodal cells, although a varying number of nuclei 
become enclosed in cell membranes and form small flattened 
cells applied to the wall of the 
embryo sac. It is to be hoped 
that a further study of the embryo 
sac of Casuarina may be made, 
employing carefully stained mi- 
crotome sections. A comparison 
with the embryo sac of Peperomia 
would be of great interest. 
The increased number of nuclei 
in the embryo sac of Peperomia, 
while intermediate in character 
between that of the typical angio- 
sperms and the lower vascular TR 
plants, might equally well be com- Fte: ee Gh a Aad ce 
pared with that of the gymmno- there were present sixteen free nuclei, of 
sperms Gr She Beterospofous = er o9 PH WEN. 
pteridophytes. The nearest approach to it is found in Gnetum,? 
where the structure is not dissimilar, no true archegonium being 
present, but the egg cell being developed from one of the free 
nuclei. However, as the affinities of Gnetum are very obscure, 
this resemblance does not necessarily imply any connection 
between Peperomia and the typical gymnosperms. 
An increased number of nuclei in the unfertilized embryo 
sac has been recorded as an occasional variant in several low 
monocotyledons, — e.g., Naias, Zannichellia, Sparganium, — but 
in all these forms the normal embryo sac is of the ordinary 
angiospermous type. : 
1 Johnson. On the Endosperm and Embryo of Peperomia pellucida, Botai- 
cal Gazette, vol. xxx, July, 1900. 
2 Lotsy. Contributions to the Life-History of the Genus Gnetum, Annales 
du Jardin Botanique de Buitenzorg, tome xvi (1899), pp. 46-114. 
Karsten. Beiträge zur Entwickelungsgeschichte der Gattung Gnetum, Bota- 
nische Zeitschrift, Bd. l, 1892. 


