CARPOSPORE^. 
287 
spherical cushion ; the cellular filaments which are the result of germination branch 
somewhat irregularly in one plane, but form something like a disc ; from them rise 
up ascending articulated branches, which again branch and form the cushion. In the 
following species no ascending branches are formed, but those which cling to their 
support form a more or less regular disc. In C. irregularis this takes place by irregular 
ramifications which lie in one plane gradually filling up all the interstices, till an almost 
uninterrupted layer of cells is obtained. In C. soluta (Fig. 186), on the other hand, 
a dichotomous ramification commences in the two first daughter-cells of the germinating 
spore, with corresponding cell-division of such a nature that even at a very early 
period a closed disc of radial forked branches is formed, which either lie loosely or are 
closely crowded side by side. While in the species already named the branches arise 
laterally from cells, but never from the terminal cell of a branch, in C. soluta we have the 
first instance of dichotomy as well as regular disc-shaped centrifugal growth, a condition 
which attains the highest development in C. scutata. In this species the cells which 
result from germination remain from the first united laterally and do not form isolated 
branches ; the circular disc, when once formed, continues to grow by increase of its 
circumference, the marginal cells dividing by radial and tangential walls. This mode 
of growth may be explained in this way, that the first branches are united laterally 
and grow with equal rapidity in a radial direction, and then become divided by septa 
(in this case tangential) ; while the broadening of the terminal cell of each radial row 
corresponds with the succeeding radial division of a dichotomy. The law which prevails 
in the species previously mentioned, that only the terminal cell of a branch is divided by 
transverse septa, is exemplified in C. scutata by the marginal cells only of the disc being 
divided by tangential walls. 
The Reproduction of the Coleochaetese is brought about by asexual zoogonidia and 
by resting oospores produced sexually. The oospores do not at once produce new 
plants, but several zoospores ; and the following alternation of generations takes 
place : — The zoospores, which arise in the early part of the year at the commence- 
/ ment of vegetation from a sporocarp of the previous year, produce only asexual 
plants, or, in other words, only such as can form zoogonidia. Only after a series of 
asexual generations varying in length does a sexual generation arise, which may be 
either monoecious or dioecious according to the species. Fertilisation produces one 
oospore in the carpogonia, which clothe themselves with a peculiar layer of cortical 
cells ; and this oospore itself again developes into a parenchymatous reproductive 
body, from the cells of which the zoospores proceed in the next period of vegetation 
(Pringsheim). The zoogonidia (Fig. 187, D) may arise in all the vegetative cells of the 
Coleochaeteae ; in C. pul-vinata especially from the terminal cells of the branches ; they 
are always formed from the entire contents of the mother-cell, and escape through 
a round hole in its cell-wall. 
The carpogonium is always the terminal cell of a branch, and hence in C. scutata 
the terminal-cell of a radial row (Nägeli). The peculiar mode of its development is 
subject, according to the growth of the plant, to some, though subordinate, modifi- 
cations. One species, C. pulnjinata (Fig. 187), may first of all be examined somewhat 
more closely. The terminal cell of a branch swells up and at the same time elongates 
into a narrow sac (Fig. 187, A, og, to the left), which then opens {og" , to the right) and 
exudes a colourless mucilage. The protoplasm of the swollen part, which contains 
chlorophyll, forms the oosphere in which a nucleus is visible. The antheridia are formed 
at the same time in adjoining cells, two or three protuberances {J, an) growing out, 
which become separated by septa ; each of the cells thus formed, which have somewhat 
the shape of a flask, is an antheridium ; its entire contents form an antherozoid («) of 
oval shape with two cilia which is endowed with motion like a zoogonidium ; its entrance 
into the oogonium has not yet been observed. The effect of fertilisation is seen in 
that the contents of the carpogonium become surrounded with a proper membrane and 
form the oospore. This now grows considerably, and at the same time the formation of 
