| DEVELOPMENT OF HOLDFASTS OF FLORIDEA 259 
spore develops, the first rhizoid pierces the disk, which then 
becomes disintegrated and finally disappears (Pl. XXV/I/, fig. 
Fi) 
After attaching itself in the manner described, the spore 
elongates and divides several times in parallel planes at right 
_ mgles to its longer axis (P/. XXVII, figs. 11-13). The basal cell, 
_ fowing rapidly, produces a multicellular rhizoid at an early 
_ e; but large plantlets, which have already cut off corticating 
tills, occasionally show little or no tendency to form rhizoids 
i (Pl. XXIII, figs. 14,215,218). The primary root-cell branches into 
_ *veral rhizoids, which are increased in number by outgrowths 
from the cell adjoining the first root-cell (P/. XXT//I, figs. 17, 19, 
_ %,27). Still later, the cortications near the base of the plantlet 
develop multicellular branching rhizoids of great length. All 
femain free throughout the life of the plant, and both primary 
ad secondary rhizoids branch monopodially near the tip, and 
give rise to large multicellular disks of irregular outline 
(7. XXIII, figs. 16, 22, 23, 28). These indented clasping-disks 
ue closely crowded together, cohering so as to form a large 
munded holdfast, in which the various elements may be clearly 
‘inguished. As both of the species are upright in habit, no 
_ “condary holdfasts are developed at any point of the mature 
mAs in several other genera, the chromotaphores of the 
) ale of the holdfasts resemble those of the corticating 
' aie; 1 that those of the central axis, the former being 
ai 27 © latter irregular branching bands (2. XXV//, jigs. 17 
nd evident, therefore, that the species of the Ceramiacee 
ined differ greatly both in the manner of development and 
ot te holdfast, agreeing only in the production of one 
Points . Spermothamnion Turneri forms at various 
oes nos ae unicellular rhizoids with terminal disks, branching 
 banetiong Mt, and cortications are not developed. Griffithsia 
ena puitices a large spreading holdfast composed entirely 
q tell, oY matous tissue arising from the primary root- 
: amnion, Spyridia, and Ceramium have primary 
