130 Berridge and Sunday. 
tively small part of it, to which these words certainly do not apply* 
Miss Stopes and Dr. Fujii in their paper dealing with the nutrition 
of the archegonium (3) have evidently been led to the conclusion 
from this description that the jacket is feebly developed in Eplicdra, 
which is not the case, at all events in this species and in E. Helvetica ; 
M. Jaccard remarks in this connection “ L’enveloppe corpusculaire 
atteint chez l’Ephedra helvetica 2 a. 3 epaisseurs de cellules; elle 
constitue une veritable organe ayant un role physiologique determine, 
et pre'sente chez cette espece une importance qu’elleest loin d’avoir 
chez les Conifkres, et peut-etre aussi chez d’autres espkees 
d’Ephedra, si Ton en juge par le peu d’attention qu’y ont prete les 
auteurs ayant dtudie'e ce geure'.” From an early stage the jacket 
cells are characterized by active division, large nuclei, and a 
considerable amount of cytoplasm, and later by great individual 
growth and dense cell-contents. 
Simultaneously with the formation of the endosperm in the 
embryo-sac occurs the disorganization of the cells at the apex of 
the nucellus, giving rise to the pollen-chamber. The first sign of 
this change is the doubling of the nuclei within the cells of this 
region ; then the cell-contents are lost, and finally the walls break 
down over a gradually extending area until a funnel-shaped cavity is 
formed. The epidermis persists longer than the hypodermal tissue, 
hence the chamber commences as a sub-epidermal cavity, which 
occasionally is still closed when the ovule is mature. At the base 
of it the apical cells of the prothallium are exposed, and these grow 
up into it as a small projection ; in one abnormal case, at a late 
stage, the whole chamber is filled with prothallial tissue. 
The pollen-grains are found in the lower part of the micropyle 
and in the chamber itself, but never lying in contact with the pro¬ 
thallium. Their position when germinating suggests that at the 
time of gathering and fixing some were floating in a drop of liquid, 
and others adhering to the walls of the micropyle and pollen- 
chamber. It seems likely therefore that at the time of pollination 
the whole chamber and micropyle are full of the liquid observed by 
Strasburger at the tip of the latter, and the gradual drying up of 
this draws the grains down the narrow tube into the chamber. At 
a later period, however, when fertilization is accomplished, the 
discarded extines and ungerminated grains may be seen lying 
crowded together in the narrow base of the chamber, as if the 
1 This was written in 1894, and therefore before attention had 
been turned to the functions of the jacket cells by the work 
and views of Arnoldi and others. 
