Fertilization of the Floridee. 87 
the alternation of generations of the Archegoniata) * a still 
further complication, a regular alternation of sexual indivi- 
duals and (single or numerous successive) tetraspore-indivi- 
duals being developed. ‘This at least seems to be indicated 
with great probability by the fact that, of many short-lived 
Floridez, sexual plants are to be met with only at particular 
seasons, while neutral plants are to be found either throughout 
the year or, at any rate, for a considerable time. Certainly, 
however, no instance of such a regular alternation of neutral 
individuals and sexual individuals (which in itself might be 
regarded as a particular kind of alternation of generations) has 
hitherto been demonstrated with certainty by observation. 
eT. 
The whole process of development of the simplest Floridez 
approximates them, as has repeatedly been pointed out in 
literature, very nearly to the Chlorophycean group of the 
Coleochetez. 
In both groups of Alge the entire body of the plant is 
composed of ramified cell-filaments with apical growth, and 
the joints of which are never transversely divided, and these 
are more or less closely pressed together laterally. In both 
groups of Algz the sexual cells originate from terminal cells 
of these cell-filamentst. Small terminal cells develop from 
their entire protoplasm single naked male cells; individual 
larger terminal cells become inflated into female cells, and 
extend from their apex a longer or shorter thin trichogyne. 
But in the Coleochzetez these trichogynes open at the joint; 
the protoplasm of the female cell, even before fecundation, 
cuts off an unserviceable portion as a directive body, and 
evacuates this through the open apex of the trichogyne ; 
further, in the Coleocheetez the naked male cells are sponta- 
neously motile by means of two cilia; and, lastly, in the 
Coleochetez the fertilized ovicell first of all passes into a 
resting state, and only after this period of rest develops a cell- 
body, which leads to the formation of motile “ carpospores.” 
All these last-mentioned points, to which may be added, as 
less important matters, the difference of the assimilation 
* Pringsheim some time since (Jahrb. fiir wiss. Bot. Bd. xi. p. 6) ex- 
pressed an essentially different view of the sexual alternation of genera- 
tions of the Floridez. But it would lead us too far to enter here in any 
detail into the differences of the two conceptions. 
+ In the position of the sexual cells, according to the extant statements 
(Pringsheim, in Jahrb. fiir wiss. Bot. Bd. ii.), some species certainly show 
a different character, inasmuch as they develop their sexual cells from 
joint cells of the thallus-filaments. 
