Embryo-Sac and Embryo of Geissoloma marginata. 345 
THE EMBRYO-SAC AND EMBRYO OF GEISSOLOMA 
MARGIN A TA. 
By E. L. Stephens, 
(Newnham College, Cambridge), 
[Plate VI.] 
G EISSOLOMA MARGINATA is a small shrub, of an ericoid 
habit, confined to the South-West region of South Africa, 
and of very rare occurrence within that region. Material for the 
present investigation was obtained from a small patch growing on 
Garcia’s Pass in the Langeberge Mountains, in the south of Cape 
Colony, during a vacation botanical expedition from the South 
African College, Cape Town, 
The systematic position of this plant has been disputed, but it 
is usually regarded either as an anomalous genus of the Penteacese 1 
or as the sole representative of a separate order—the Geissoloma- 
cete 2 or Geissolomataceae 3 . The present investigation was under" 
taken to see whether the structure of its embryo-sac resembled in 
any way that found in the former order. 
A single sporogenous cell is differentiated in the young ovule, 
but as no satisfactory preparations of the stages in its division have 
been obtained, it cannot be said whether or not the usual row of 
megaspores is formed. There is, however, strong presumptive 
evidence that it does occur. Thus, in Fig. 1, which shows the 
youngest stage of the embryo-sac seen, the developing megaspore 
is crowned by a deeply-staining mass which probably represents 
the remains of the megaspore row, and a similar appearance has 
been seen in several other preparations at the same stage. More¬ 
over, the appearance of the first four nuclei formed in the embrjo 
sac (Figs. 1—3), suggests that they are the results of ordinary 
nuclear divisions, and not of meiosis. 
The eight-nucleate is reached in the usual manner (Figs. 1—4). 
As soon as the eight nuclei are formed they begin to show 
differences in size and staining properties, and this differentiation 
rapidly becomes very marked. The upper polar nucleus at once 
1 Bentham and Hooker. Genera Plantarum III. London, 1S80. 
p. W3. 
2 Sonder, W. Beitrilge zur Flora von Sudafrica. Linniea, 
XXIII. (Halle, 1850), p. 105. 
De Candolle. Prodromus XIV. Paris, 1856, p. 491. 
3 Engler. Syllabus der Pflanzenfamilien. Berlin, 1909, p. 177. 
