42 BOTANICAL GAZETTE - [rom 
pogenic branch, which seemed to be followed by changes in 
the appearance in the lower ones, both following upon fertiliza- 
tion. 
At this stage the supporting cell, now rich in _proto- 
plasm, increases in size and cuts off a cell, which, in turn, becomes 
larger, though without taking a deeper stain, and becomes the 
placental cell. From all sides of this cell, cells arise which are 
distinguishable at once by their large nuclei, and it is by their 
subsequent division that the lobes of spores arise, each cell thus 
cut off from the placental cell developing into one lobe. Each 
cell cuts off small cells from the sides and end, and soon assumes 
a cuneate form, the individual segments having a similar or a 
clavate form. Each lobe consists for a time of a compact mass 
of cells, but as the cells separate and become rounded off as 
spores, it develops into a branched tuft made up of loosely con- 
nected chains of ovoid or elliptical spores, developed in basipetal 
succession, each with a large nucleus. The process, however, is 
apparently not strictly uniform in all cases, as may be seen by 
comparing figs. 75-19. The lobes arise successively, and thus 
different stages of spore formation may be seen in a singie prep- 
aration (figs. 15-19). According to Harvey? each lobe con- 
stitutes a favella, and thus several favelle are contained withina | 
single involucre, while Farlow regards the lobe collectively as 4 
constituting one favella. : 
The favelle, as well as the vegetative cells of the thallus, are — 
surrounded by gelatinous membrane, which has been omitted in 
the figures for the sake of clearness. Around the vegetative — 
cells it is so swollen by the glycerin as to be very evident, but 
it often remains in such close contact with the lobes of spores — 
as to be detected with difficulty. 
Directly after fertilization, as the central cell begins to take 
a deep stain, the growth of the involucral branches begins. The 
basal cell of the fruiting branch cuts off cells, which remain 
small and oblong, but from each of which another ‘cell is cut off, § 
9 Nereis Boreali-Americana 2:227. 1853. Smithsonian Contributions to Knowl- 
edge No. 5. 
