Fertilization of the Floridex. 9 
tions have also hitherto failed in detecting, with certainty, in 
these cells either any locomotive organs, or, indeed, a striking 
spontaneous mobility of any kind. But one series of observa- 
tions* leads me to think that the prevalent supposition, ac- 
cording to which the spermatia only reach the female cells 
passively by the movement of the surrounding water, by no 
means entirely exhausts the facts; and I would therefore 
prefer, for my own part, to leave the question of the mobility 
of the isolated spermatia still undecided. 
Hr. 
The female sexual cells of the Floridez originate without 
exception from the terminal cells of longer or shorter lateral 
branches of the whole system of ramification of the filaments 
of the thallus. These branches are frequently formed only 
as secondary lateral branches after the formation of all the 
other ramifications. Sometimes they are confined to a very 
small number of cells (two or three, rarely one), sometimes they 
attain a greater length; and while sometimes they do not 
differ in structure from the other neighbouring sterile branches, 
in most cases they may easily be distinguished by their formt, 
the size of their cells, or the different branching of their joint- 
cells. In all cases, however, their terminal. cell finally be- 
* For example, when observing living spermatia of Polysiphonia elon- 
gata, Grev. (at Heligoland), I quite distinctly saw a single spermatium 
travel slowly through the field of the microscope, while the other sper- 
matia lay quite still. 
Several times I also saw spermatia of the same Polysiphonia attached 
in such a manner that the globular spermatium stood off from the sup- 
porting surface about twice the length of the diameter of its body, 
although still firmly adhering to it, as it accompanied all (even the 
smallest) movements of the supporting body with pendulum-like oscil- 
lations. It was natural to see in the filamentous connecting cord which, 
from what has been said, it must be assumed attached the spermatium 
to the supporting body, the cilium of the spermatium which has hitherto 
been sought in vain. But, unfortunately, notwithstanding all my endea- 
vours, I was unable clearly to detect this supposed cilium, often as I 
thought I could discern it. 
A further indication of spontaneous mobility in the spermatia of the 
Florides is to be found in the fact that in Batrachospermum the spermatia 
must penetrate through the gelatinous envelope of the branches of the 
thallus in order to reach the apex of the completely immersed carpogonia, 
They can hardly be capable of such penetration without some proper 
(perhaps amceboid ?) mobility. 
+ These branches appear to be particularly noteworthy on account of 
their similarity to the “ procarpia’’ of the Collemacee, as in Batrachosper- 
mum Julianum, Aycangeli, according to the description of Arcangeli 
(Nuov. Giorn. Bot. Ital. xiv. 1882, pp. 160 et seqg. tav. v. figs. 1-8), in 
which species the female cell occupies the apex of a short-jointed spirally- 
contorted branch. 
