256 
Transactioris of the Royal Society of South Africa. 
We may first consider some characters of the Angiosperm-sac which 
appear to possess importance in this connection. In the form most 
commonly met with, the 8-nucleate sac, the nuclei show a considerable 
degree of physiological differentiation ; six of them are incorporated in units 
of protoplasm, two remain free ; of these, only one normally functions as a 
gamete ; three, frequently increased by division (antipodals) seem either to 
be of no physiological account or to be concerned in the nutrition of the sac 
in its early and middle stages ; two (synergids) are very definitely associated 
with the oosphere in the egg- apparatus ; the two free nuclei fuse to form the 
primary endosperm-nucleus. There are, however, many cases in which a 
much lower degree of differentiation obtains. The function of the odsphere 
may be performed by a synergid ; * embryos are said also to arise from 
antipodal cells and from polar nuclei ; f in Alchemilla:|: all the antipodals^ 
as well as the polar-nuclei, are included in the fusion which constitutes the 
primary endosperm-nucleus. 
Table I. 
Total 
sac-nuclei. 
Synergids. 
Fusinof 
sac nuclei. 
Antipodals. 
Euphorbia virgata^ . 
16 
1 
14 
0 
E. jproceraW .... 
16 
2? 
4 
3? 
E. 'palustris'^ .... 
16 
2 ? 
4 
3.P 
Pejperomia hispidula§ 
16 
1 
14 
0 
P. pellucida^ .... 
16 
1 
8 
6 
Penaeaceae§ .... 
16 
2? 
4, 5 or 6 
3? 
Gunnera§ ..... 
16 
2 
7 
6 
Some Podostemaceae§ 
4 
2 
0 
0 
Cypripedium .... 
4 
1 
2 
0 
The sac-nuclei are frequently less or more than eight in number. In 
these we find varying degrees of specialisation and varying numbers of 
f using-nuclei. The numbers of synergids, fusing-nuclei, and antipodals found 
in some of these are contrasted in Table 1. 
These differences in the number and behaviour of the sac-nuclei are very 
strict Angiosperm sense." The appearance in Ephedra of an endosperm of the same 
character as that of Gnetiim is not improbable, and its recognition would be of great 
interest. The facts at present known regarding this " nutritive mass " are not 
sufficient to justify a comparison. 
* Coulter and Chamberlain, 1903, figs. 102, 103. 
t Loc. cit., Gruignard, ex 221 ; Opperman, 1904. 
% Murbeck ex Coulter and Chamberlain, 1903, p. 93. Apparently the number 
of fusing-nuclei is very inconstant. 
§ See Table II. 
II Modilewski, 1908. 
IT Modilewski, 1911. 
