1916] ROE—SPLACHNIDIUM 403 
Some of the hairs, as in Fucus, are shed later and the lining 
cells put forth new papillate growths which elongate into sacs 
(fig. 22) which are ultimately filled with spherical bodies (fig. 24), 
variously described as zoospores (10, 11) and gametes. AGARDH (1), 
Harvey (4), Hooker (5), and Larne (8) all describe Splachnidium 
as dioecious, although no one of these authors reports having 
actually observed antheridia. Larne speaks of oogonia “obscurely 
pedicelled,” developed from the lining of the conceptacle, each 
oogonium giving rise ‘to a large number of oospheres, thus differing 
from all other Fucaceae that have hitherto been described. Each 
oosphere is very small, compared with the oospheres of other Fuca- 
ceae.”” In another paragraph he states that “as antheridia have 
never been observed it is just possible that these hairs [apical 
hairs] may be antheridial in function.” The writer’s feeling is that 
the reproductive sacs contain isogamous gametes. However that 
may be, the conceptacles, at the time the reproductive bodies are 
ready for discharge, still contain the “initial” as a conspicuous 
feature (fig. 23). 
Discussion 
Murray (11,12) and also MircHELL and WuitTING (10) speak 
of the “modified cell” of Splachnidium as homologous with the 
“initial” of Fucus; and yet these same authors make this “unique 
cell” one of the reasons for separating Splachnidium from other 
families. The similarity holds true only in so far as the con- 
ceptacle is concerned, where, as previously shown by the writer 
(14), the conceptacle in each genus is the result of arrested develop- 
ment and partial breaking down of a portion of the external layer 
of the thallus followed by great activity of abutting tissue. The 
initial row is in no way comparable to the true apical cell of 
Fucus, segments of which are the basis of all tissue of the 
thallus. 
The fact that the initial row of Splachnidium occurs wherever there 
is great activity is additional evidence for the simple origin of the con- 
ceplacle. Splachnidium is a particularly favorable plant for study 
along this line, since the same structure accompanies ordinary 
vegetative growth as well as reproductive activity. 
