258 BOTANICAL GAZETTE [ocTopsr 
outgrowths of the larger cortical cells develop disks and enter 
into close mechanical union with the main holdfast, adding greatly 
to its efficiency. The secondary rhizoids thus formed are destitute 
of cortications (P/. XXT/, fig. 29) and are easily distinguished 
from those ordinary branches which, coming in contact with the 
substratum, develop holdfasts (P. XXVI, figs. 26, 28a). Spyridia 
creeps not only by means of such branches but by the aid of 
masses of uncorticated hair-like rhizoids, which may be formed at 
any point (Pi. XXII, fig. 286). One curious instance was noted 
of short rhizoidal outgrowths from each of the central cells ofa 
trailing branch, the cortical cells being unmodified (71. XXII, 
Jig. 27). The differences in the chromatophores are similar to 
those noted in the Rhodomelacez. ; 
Ceramium differs in many respects from the other genera 
described. Both Ceramium rubrum (Huds.) C. Ag. and ¢. alee 
tum Harv. were carefully studied and found to agree closely i 
so far as the early development of the plantlet and the forma- 
tion of the rhizoid are concerned. Shortly after it is sow”, the 
Spore produces a cell-wall (P/. XX///, fig. 24) and a well-defined 
temporary holdfast. The latter is a granular disk of — 
thickness, and mucilaginous in character, attached to the base 0 
the spore (Pl. XXTI/, fig. ro). The granules, embedded inne 
matrix, are often arranged in lines ‘radiating from the axis to 2 
rim of the disk (Pl. XXTV/, fig. 25). The distances pace 
granules being least in vertical planes, the disk appears den a 
when viewed from the side. This peculiar body does not a 
to the ordinary tests for cellulose, and is not dissolved after P 
longed treatment with dilute potassium hydrate. It is 
; - 
neither by Hanstein’s aniline blue nor safranin; but the gO ss 
lar portions stain deeply with haematoxylin and with Congo 
paged fore, 
and the whole with Bismarck-brown. The disk a me: | 
distinct from the cellulose wall of the spore and heer 
ally from ordinary vegetable mucilages, though 
closely allied to the latter. This temporaty t. but has 
peculiar to plants existing in an unnatural environmen" ve 
been found in very young plants growing on Chordati2- 
holdfast is 
fi 
