576 DR. J. B. HICKS ON THE GONIDIA AND 
on any side and form a branch, which, segmenting, becomes a true filament (PI. LVII. 
fig. 4 c). Not unfrequently these cells retain their linear form, especially after the cell- 
wall has become dense by age, though sometimes whilst the linear growth is very 
active. In the latter case, the contents of these actively growing cells occasionally be- 
come more or less homogeneous, with a distinct central nucleus (PL LVII. fig. 15 c), 
and much resemble a single cell of Palmoglcea. As a rule, when the separated cell 
retains its linear form, and is in active growth, it does not in general branch laterally 
for some time, but continues in the linear direction by binary division for a considerable 
period. But frequently, under certain conditions, the terminal cells, instead of possessing 
an elongated form, become more or less globular, which shape is not confined to the last 
one, although it may be more marked in it, but is frequently seen in the four or five (or 
even more) nearest the end of the branch (PI. LVII. figs. 10 b, 13, 15). Of these the terminal 
one possesses the greatest tendency to become free, although all of them do so very readily. 
These free cells, then, appear quite globular, with green contents, which are sometimes 
granular, though more frequently more or less homogeneous, with or without a central 
nucleus, as is observed in the gonidium of the Lichens (PI. LVII. fig. 10 c). Where 
there is this tendency to the globular form of the cells near the extremity of the filaments, 
there is also a disposition in the cell-contents to become more deeply green. This is 
partly owing to the deeper tint the contents assume, and partly to the closer crowding of 
the chlorophyll-granules of which they are composed. 
These terminal globular cells have, under certain conditions, a tendency to become 
quiescent ; the cell-wall then becomes thicker, and, as in the cells mentioned before, it 
frequently assumes a reddish-brown colour, whereby the whole becomes very dark 
indeed, so as to become almost a black ball (PI. LVII. fig. 15 b, PL LVIII. fig. 16). These 
cells also segment in a less regular manner than do those of the same filament below it ; 
there is an imperfect tendency to branch. The cells thus formed at the side tend to the 
globular form (PL LVIII. fig. 16 b, c). The cells, thus altered in appearance, generally 
detach themselves in groups of two or three cells to each, and can be carried about by the 
elements. They, however, occasionally do not become globular, but more or less oval, 
springing from the end of one cell in groups of three or four, as shown at PL LVII. 
fig. 15 b, each cell of which, becoming free, appears like the cell of a Palmogleea, especially 
as in some the contents become homogeneous, with a central nucleus. As this mode is 
observable on the branch of the same filament which possesses the other forms at the 
same time, this peculiar appearance is thus traced to its true origin, which would 
otherwise scarcely be guessed at. The cells are more active than the globular forms ; 
and some, as soon as they separate, begin to segment linearly, and to form a filament. 
These conditions were looked upon as Confervse by the older algologists, under the 
name of C. multicapsularis (PL LVIII. fig. 16; see Dillwyn's ' Conferva ') and C. 
umbrosa (PL LVII. fig. 15 6). I have already pointed out Kutzing's arrangement of 
these and other forms. 
These free dark cells with crowded contents, when influenced by warmth and moisture, 
form branches in the manner already described, thus giving rise to new filaments. 
They, however, may become mother-cells, as will appear below. In PL LVIII. fig. 16 a 
