F am. x v i i . PA LM E L L EÆ .
Char. Frond consisting o f a gelatinous colourless fluid, in
which are immersed numerous globules, containing the colouring
matter.
45. P A LM E L L A Lyngb.
Char. “ Frond mucous, indefinite, enclosing hyaline globules,
in which the colouring substance, continuous, and never
granular, is situated. Gramdes fir s t evolved in the
mucous substratum o f the frond, at length constituting new
globules." — Meneghini.
Derivation. From iraXgos, vibration ; in allusion to tbe
gelatinous nature of the frond.
“ This genus differs from all the other genera of Nosto-
chineæ, especially in its frond, which, from the beginning, is
indefinite. In other species the frond preserves its defined
form during the entire course of its existence, or at least in the
beginning describes a certain form with peculiar limits. But
in this, the frond never can possess a definite form, on account
of the nature of its generation and evolution ; for the globules
living in the mucous substratum of the frond, otherwise
very similar to those of other Nostochinea;, differ as much
as possible from aU others, in the fact of the colouring matter
in them never becoming granular, and that, because the granules
from which new globules proceed are neither evolved
nor undergo evolution in the interior of the maternal globules ;
for tliese are either altogether resolved into mucus, or pour
out the mucous substance which they contain, which substance
not being covered with an involucre, is indefinitely
diffused, and is circumscribed only by external circumstances.
B u t in this mucosity minute punctated points or
granules appear, which little by little are evolved, and at
length attain to the dimensions of the parent globules. The
form, therefore, of the frond is necessarily indefinite. By
reason of the absence of the vesicles nourished in the interior
of the larger globules, the material included in the globules
is altogether continuous, fiuid, and never granular. A t length,
when effused, the presence of dots or minute granules dispersed
through the mucous substratum afford distinct characters
whereby the genus may be easily distinguished by
microscopic examination.
In the genus Palmella, as limited by himself, Meneghini
describes two species, Palmella cruenta and P. montana.
The first of these Meneghini takes for the type of his genus
Palmella, and to this only do his observations in any measure
apply. The other species seems to me to be of a nature
altogether different, indeed scarcely congeneric. In P. cruenta
the grains or cells are loosely scattered through the mucous
matrix, and their contents are usually, as Meneghini describes
them, uniform and homogeneous. In P. montana, P. Ralfsii,
P. virescens, and P. grumosa, the cells are collected into little
clusters, and their contents are nucleated. Meneghini, therefore,
would not appear to have studied the second species of
his genus P. montana, which, as well as the other species
Palmella Ralfsii, P. virescens, and P. grumosa, ought, in all
probability, to be included iu a distinct genus. Palmella cruenta,
on the one side, evidently bears a close relation to Protococcus
nivalis, from which indeed it principally differs in the fact
of the globules being distinctly immersed in gelatine, while
in P. nivalis they are free. P. montana, &c., on the other
hand, exhibits a relation almost as close to Hcematococcus, from
which genus it differs in the same manner as Protococcus
nivalis and Palmella cruenta differ. The globules of Hwma-
tococcus sanguineus exhibit the same nucleated appearance as
do those of P. montana, P. Ralfsii, &c.