124 MR. HENFREY ON THE DEVELOPMENT 
a less definite outline than the others. Finally, some appeared unable to extricate them- 
selves from the sperm-cell, and carried this along attached to the posterior extremity 
(fig. 44). This vesicle attached to the spermatozoid has been described by some observers 
as formed by the swelling of the extremity of the filament after its exit from the sperm- 
cells, therefore as constituting an integral part of the structure of the spermatozoid ; but 
I believe this to be an error. 
In one case I saw an appearance which seemed to indicate the existence of a hair-like 
produetion of the posterior extremity of the spermatozoid, like that figured by Hofmeister. 
A spermatozoid moving rapidly forwards in the water dragged after it, at a little distance, 
a small mass of mucilage (fig. 425); the bond of connection was invisible, and therefore, 
most probably, must have consisted of a capillary process. I never saw any hair-like tail 
in specimens suddenly paralysed by iodine, but it may have escaped notice from its 
tenuity; on the other hand, it may possibly be only found in the most perfect state of the 
X spermatozoid, and since these are examined under artificial conditions, often causing the 
rupture of the antheridia before their contents are mature, the most perfect condition may 
only be met with occasionally. 
III. THE ARCHEGONIUM. 
In the description of the development of the prothallium, it has been stated that a 
thickened, cushion-like mass is formed in the central region, by the time the general form 
has become complete (fig. 51). "This central mass is composed of several layers of cells, 
and, projecting from the general surface, does not reach quite to the inner extremity of the 
anterior notch of the prothallium, so that an inclined surface is produced looking somewhat — 
forwards toward the notch (fig. 52). Upon this arise the archegonia, which are variable 
in number, seldom however exceeding six or eight. 
The earliest rudiment of the archegonium is the embryo-sac, as it may be termed, con- 
sisting of one of the cells of the thickened cushion, separated by a single cell from the 
(inferior) surface of the prothallium (figs. 54—57 a). A cell, destined to become an embryo- 
sac; is found surrounded by a circle of cells of smaller size than those of the surrounding 
tissue, and formed by the production of walls in the cells immediately bordering the 
embryo-sac, tangental to the circumference of the latter, which thus becomes defined by a 
wall of small cells surrounding it (figs. 55, 57 b). Cell-division also takes place in the 
cells beneath the embryo-sac, and these multiply so as to form a collection of condensed 
tissue enclosing the embryo-sac at the sides and below (figs. 66, 67 6), visible through the 
cells of the surface of the prothallium (figs. 54, 56) before the external structure is formed. 
The commencement of the development of this consists in the enlargement of the cell sepa- 
ve the embryo-sac from the surface, and its division into two cells by an inclined wall, 
e larger of these being again divided by another partition at right angles to the former, 
ie seen from the (under) face of the prothallium (fig. 52), the superficial cell seems 
Goti a vast À un not follow the development of the cells, step by step, onward 
first cell : a. : En that they go on repeating the mode of subdivision of the 
etie ies | say, the process is as follows: the original cell, a, divides by an oblique 
an upper, 6, and lower, a, the latter being divided by a radial septum into 
