DEVELOPMENT OF CONCEPTACLE IN THE FUCACE.E. 45 
Fucus vesciculosiis. 
The conceptacles of F. vesciculosus resemble those of 
F. platijcarpus rather than those of F. serratus, but the 
division of the initial cell is less frequent than in the former 
species. The development of the neutral is similar to that of 
the sexual conceptacles. 
Ozothallia nodosa. 
My materials, collected in August, 1879, supplied only the 
youngest stages of conceptacles. In these the initial cell and 
the divisions of the surrounding tissue correspond to those in 
the genus Fucus. The basal cell is, hoAvever, not so promi- 
nent as in F. serratiis. In this point, and also in the general 
form of the conceptacle, Ozothallia appears to hold an inter- 
mediate position between Fucus and Himanthalia. 
Halidrys siliquosa, ^ 
Viewed from above the young conceptacle of Halidrys 
appears in all respects similar to that of Fucus. In longi- 
tudinal section the initial cell appears in some cases as in 
Fucus ; but, in the large majority of cases, divisions occur in 
it, resulting at an early period in two or, in some cases, more 
than two cells. The basal cell divides at first by avails 
strongly inclined to one another. The cells thus produced 
do not at an early stage divide by walls parallel to the 
surface of the cavity. The result is that the conceptacle 
usually appears, as in fig. 9, as though lined by a layer of 
cells continuous with the limiting layer ; but as part, at 
least, of this tissue is derived from the basal cell, this con- 
clusion is inadmissible. Meanwhile, the initial cell (or grou]) 
of cells) has been completely thrown off by the s^velling of 
the wall dividing it from the basal cell. 
Later, as in the other plants of the group, the cells of the 
lining tissue put forth papillae which develop further into 
hairs. 
Himanthalia lorea. 
Here we have a departure from the type of Fucus. Close 
to the apical cell of the fertile branch the cells of the limiting 
tissue, by means of repeated divisions parallel to the surface 
of the thallus, grow^ out into multicellular hairs, almost 
every cell bearing one. As the cells of this tissue con- 
tinue to divide, some of the hairs arc thrown off, and the rest 
remain scattered over the surface. These isolated hairs 
consist of an apical part, in which the cells are in various 
stages of decomposition ; a central part where the cells form 
