134 Oogenesis & Embryogeny in Ephedra distacha. 
Normal Embryogeny. 
Certain archegonia contain a small number of nuclei varying 
from two to eight, often linked together by spindle fibres and 
showing cell-plates between them. These can only arise from the 
egg, probably after fertilization, for the adjacent jacket cells are 
degenerating and their nuclei do not show that tendency to escape 
into the egg-cell which is evident in most ovules at this period. 
When as many as eight such daughter nuclei of the egg are 
present, some are found to have passed into the pointed base of 
the archegonium and there developed into pro-embryonal cells, as in 
Fig. 14. In the section figured, four pro-embryonal cells are 
visible; one other which is present does not appear here. They 
are separated from one another by delicate cell walls, and the dense 
cytoplasm within each cell shows marked radiation from the 
nucleus outwards. The free nucleus higher up in the archegonium 
is one of a group of three, making the total number of daughter 
nuclei of the fusion nucleus eight. This mode of formation of 
the pro-embryos corresponds with the brief account given by 
Strasburger in “ Die Angiospermen und die Gymnospermen ” for 
E. altissima (8), though the daughter nuclei do not appear in that 
species to pass into the base of the archegonium, but to remain 
scattered throughout the egg-cell. 
The further development of the pro-embryonal cell also agrees 
with the account given for E. altissima. Each cell, independently 
of the others, gives rise to a long tubular suspensor, which makes 
its way through the loose tissue of the upper part of the 
gametophyte to the nutritive region below. In this species it is very 
long and its course among the endosperm cells very difficult to trace. 
Sometimes a transverse wall is formed separating the suspensor 
from the original pro-embryonal cell; its position is very variable 
and frequently it is not developed at all. A small embryonal cell 
is cut off from the tip of the suspensor; the oldest material obtained 
from Brittany, gathered on June 20th, showed this cell divided by 
two transverse walls, thus forming a three-celled embryo (Fig. 15). 
The method of embryogeny outlined above is essentially 
a Gymnospcrmic one, and we may even regard the gathering 
together of the daughter nuclei in the base of the archegonium in 
this species as possibly indicating a tendency to form a multicellular 
pro-embryo. 
(To be continued). 
R. Mauley, Printer, 151, Whitfield Street, Fitzroy Square W, 
