1899] DEVELOPMENT OF HOLDFASTS OF FLORIDEZ 247 
variations are most important factors in the life and distribution 
of marine alge, but a. comparison of many cultures of the same 
species indicates that differences in the conditions which pre- 
vailed in the laboratory affected neither the form nor the order 
of development of the plantlet. It was difficult to keep the 
young plants healthy for more than three or four weeks; and 
during a few days of intense heat, in August 1896, all ceased to 
grow, were attacked by bacteria, and finally died. 
Both carpospores and tetraspores were germinated and most 
closely resembled one another in their development. In some 
tases, however, tetraspores attached themselves to the substratum 
less readily than carpospores. This is regarded by Brannon 
(2) as an adaptation to the immediate distribution of the species. 
Every day, slides upon which spores were growing were 
examined and drawings of living plantlets were made. Perma- 
wnt mounts for comparative study were prepared at regular 
imervals and mature holdfasts were preserved in alcohol or in 
} per cent. formalin in sea water. 
The species selected for investigation belonged to the Rho- 
dymeniales, with the exception of one member of the Rhodo- 
: Ey tase Rhabdonia tenera J. Ag. The carpospores of this 
| Pat attach themselves firmly to the slides in nine hours; a very 
— Mlicate outer layer, probably of mucilage, may be observed, but 
oa 
eh 
‘at hardly be distinguished from the cell-wall (Pl. XXV, fig. r). 
ees an irregular layer of a coarsely granular substance 
beret the plantlets, and in one, a thick mucilaginous disk 
“yohagd at the base ; these appearances were most aon a 
(Pr. is were doubtless due to slightly abnormal conditions 
ho 7, 8). After attaching themselves, the spores 
: Wenty-t oy *Bter upon a segmentation stage, and within 
the : a hours two divisions are made. The first separates 
PI Xu by means of a vertical wall into two equal cells 
* Figs. 2,3). Three and four-celled stages result from 
tight division of the two primary cells in vertical planes 
by obli ngles to the first wall; other cells are cut off from these 
We walls, and thus an irregular spherical mass 1s formed. 
