) DEVELOPMENT OF HOLDFASTS OF FLORIDE 257 
extremity of the root-cell and separated from it by a wall (PZ. 
ANU, figs. 37-33, 37,38). A multicellular holdfast results from 
the division and branching of the primary root-cell and of the 
oldest cell of the disk (Pt. XXT//, figs. 34, 36), and is further 
_ srengthened by a few corticating rhizoidal filaments. In mature 
_ Callithamnion Baileyi Harv. the intracuticular rhizoids are more 
_fmerous. They arise from the lower angles of the central cells 
from the basal cells of the branches. Thence they descend 
through the walls of the monosiphonous frond to the holdfast, 
_ Where they branch freely and spread out in various directions, 
_ lorming, with the filaments arising from the cells of the primary 
tisk, a flat circular holdfast (Pl. XXII, figs. 35, 39). 
The carpospores of Spyridia filamentosa (Wulf.) Harv. germi- 
mie very readily. The mucilaginous secretion, by which the 
‘Peres are first fastened to the substratum, can hardly be dis- 
‘nguished from the wall of the spore (Pi. XXII, fig. 11). The 
eo frst forms two unequal cells, the smaller of which becomes 
the pamary root-cell, the larger divides by parallel walls so as to 
form a short filament (PZ. AXT/, figs. r2-14). Asa rule, no long 
Aan thizoid is formed, but occasional exceptions are found (PZ. 
‘ AM, fig. 78). Though variations may occur (2. XXV//, fig. 15), 
1 first Corticating cells are usually cut off from the upper 
hg the central cells before the formation of the discoidal 
_ oSast begins (Pl. XXTI, jig. 16). Sooner or later, however, the 
aa oaelaa divides in several planes parallel to the longer 
q tds of . and thus produces a flat multicellular disk, the 
21) 7 oa separated by walls (P?. XXTI, figs. 15,17, 19 
4 i. ~ tst the primary disk is but slightly lobed, but the 
; Ito. 8!Ve rise to short filamentous outgrowths, which branch 
j oy (Pl. XXII, figs. 21, 22). Rarely a lateral 
" Weaflam: a the primary root-cell, which is then prolonged 
| by Retin. (72. XT, fig. 23). The cells of the primary hold: 
a to divide, and with them are combined _rhizoi- 
» Which have their origin in the corticating cells of 
Odes of the frond and grow through the cell-walls 
tratum ot XX jigs. 24, 25). Free filamentous 
