CARPOSPORE^. 
299 
whip-shaped filaments, which, being coiled round and round, fill up the interior of the 
globule (Fig. 198, B). Each of these filaments (the number of which amounts to about 
200) consists of a row of small disc-shaped cells (Fig. 198, D, i^), numbering from 
100 to 200. In each of these 20,000 to 40,000 cells is formed an antherozoid, a slender 
spiral thread, thickened behind, and bearing at its pointed end two long fine cilia 
(Fig. 198, G). When perfectly ripe, the eight shields fall apart, their spherical 
curvature becoming diminished; the antherozoids leave their mother-cells and move 
about in the water. This breaking up appears generally to happen in the morning, 
and the antherozoids are in motion for some hours, till evening. 
The mature Carpogon'ium (Nucule), when ready for fertilisation, is a longer or 
shorter prolate spheroid ; it is placed upon a short pedicel, visible externally only in 
Nitella, and consists of an axial row of cells, closely surrounded by five tubular cells 
which are coiled round it spirally. The whole must be considered as a metamorphosed 
branch. The lowest cell corresponds to the lower internode of a branch; it bears a 
short central nodal cell, around which the five enveloping tubes spring like a whorl of 
leaves. Above the nodal cell rises the peculiarly developed apical cell of the branch, very 
large as compared to the other parts, and ovoid. At its base, immediately above the 
nodal cell, an inconspicuous hyaline cell is separated at an early stage in Chara\ in Nitella 
a somewhat disc-shaped group of similar cells takes its place, which have been termed 
by Braun ' Wendungszellen,' and which I consider as forming a very rudimentary 
trichophore. The large apical cell of the carpogonium is filled with a number of 
drops of oil and grains of starch as well as with protoplasm ; it contains pure hyaline 
protoplasm only in its apical region (the apical papilla). The enveloping tubes, which 
contain a quantity of chlorophyll, project above the apical papilla and bear the Cro^n, 
consisting in Chara of five larger, in Nitella of five pairs of smaller cells, which have 
already been separated at an early stage from the enveloping tubes by septa. Above the 
apical papilla and beneath the crown, which forms a compact lid, the five enveloping 
tubes form the neck which encloses a narrow cavity, the apical cavity ; above the 
papilla this cavity is of an obconical figure narrowing upwards, the five segments 
of the neck projecting and forming a kind of diaphragm, through the central very 
narrow opening of which the union with the upper roomy part of the apical cavity 
is effected. This is closed above by the crown ; but, at the time of fertilisation, it opens 
externally by five clefts between the coronal cells ; and through these clefts the anther- 
ozoids penetrate into the apical space filled with hyaline mucilage, to find their way into 
the apical papilla of the oosphere, where the cell-wall is apparently absent. After 
fertilisation the chlorophyll-granules of the envelope become reddish-yellow, the wall of 
the tubes which lie next the oosphere increases in thickness, becomes lignified, and 
assumes a black colour ; and thus the oosphere, now transformed into a carpospore, 
becomes surrounded by a hard black shell with which it falls off", to germinate in the 
next autumn or spring. 
With regard to the various processes of development, I will here describe only those 
of the antheridia and carpogonia. 
Antheridia. The order of development of the cells has already been exhaustively 
described by A. Braun in the case of Nitella syncarpa and Chrra Baueri ; it agrees with 
that of Nitella flexilis and Chara fragilis. In Nitella the termin^il cell of the leaf becomes 
the antheridium ; the oldest leaf of a whorl first forms its antb ridium, the others follow 
according to their age ; the antheridia are recognisable even in the earliest state of 
the whorl of leaves. In Fig. 200, is shown a longitudinal section through the apex 
of a branch, t being its apical cell ; its last-formed segment has already been divided 
by a septum into a nodal mother-cell /Tand an internodal cell lying beneath it; beneath 
this lies the node with the last whorl of leaves ; h is its youngest leaf, bK the ba:al node 
of the oldest leaf which already consists of the segments I, II, III', a is the terminal cell 
of this leaf which is becoming transformed into the antheridium. While the antheridium 
is becoming developed, the leaf also undergoes still further changes which must be first 
