DEVELOPMENT OF CONCEPTACLE IN THE FUCACEvE. 49 
matogen or Periblein of the higher plants. The mere fact 
that the cortical tissue of Fucus is derived by constant 
direct division from the limiting tissue is sufficient to show 
that the two are in the closest genetic connection, and that 
therefore the difference of origin of the lining tissue of the 
conceptacle is of very slight importance. 
Upon the homology of the sterile conceptacle Faser- 
griibchen”), and of the sexual conceptacle, I need here 
offer no further remarks. 
In comparing the neutral hairs in the male and female 
conceptacjes of dioecious species, I find it the rule that no 
hranching occurs in the neutral hairs of the female concep- 
tacle. It may be noticed in connection with this that no 
secondary lateral formation from the pedicel of the oogo- 
nium has been observed. In the male conceptacle even 
before the formation of antheridia the hairs hra7ich, they do 
so according to a monopodial racemose system. It has been 
seen (cf. fig. 12) how the formation of antheridia modifies 
the branching to a sympodial system. The antheridia were, 
however, observed to arise also on the apex of outgrowths 
from single cells bordering on the cavity of the conceptacle 
(fig. 8). Comparing antheridia in the state represented by 
fig. 8, i, with the oogonia as represented by Thuret (Etudes 
Phycologiques, plate xii), we cannot fail to see a complete 
morphological identity. Both are produced by the out- 
growth of a cell bordering on the cavity of the conceptacle. 
In both cases a cell-wall tangential to the inner surface of 
the conceptacle divides an apical sexual cell from a basal 
neutral cell. It is a matter of but minor importance that 
the basal cell of the antheridium may by lateral growth 
produce a second antheridial cell. This may be regarded as 
an outcome of the general rule, that where the male organ 
is endowed with free motion, it is produced in greater pro- 
fusion than the female organ. 
We may conclude then that the antheridium of the Fucus 
group is, at least in some cases, morphologically identical with 
the oogonium. 
Lastly, I must record my thanks to Professor de Bary, of 
Strasburg, for his kindness in allowing me the use of his 
laboratory, and also for his interest and suggestions during 
part of my work. 
VOL. XX. NEW SER. 
D 
