Holtz: OBSERVATIONS ON PELVETIA. 35 
sections like Avg. 27 are met with in which it is clearly seen 
that these lateral basal cells are not the daughter cells of the 
central basal cell a, but that they are the basal cutoffs of the 
epidermal cells above them. They are, therefore, codrdinate 
with the basal cell a. The cells e and fare later cutoffs which 
the epidermal cells g and / succeeded in cutting off before be- 
coming affected by decay. On account of less resistance from 
the cavity than on other sides these lateral basal cells grow 
usually in the shape shown in /7g. 79. 
To summarize my conclusions on this point, the conceptacle 
originates by a few contiguous epidermal cells cutting off basal 
cells, Azg. 77, which are meristematic, dividing principally 
periclinally into half a dozen or more tiers of cells. Directly 
over this meristematic mass of cells, whether by the tension 
produced by the growth of the cells below, or otherwise, one or 
several epidermal cells begin to show signs of decomposition. 
The disintegration proceeds and the cells collapse (/7gs. z9 and 
2r), and a cavity is begun. The disintegration spreads to 
neighboring epidermal cells and to the cells in the meristem 
below (/7gs. 27, 23 and 25). By their decay the cavity is en- 
larged. The deeper and marginal cells in the meristematic 
mass do not disintegrate, but in the end make the inner wall of 
the conceptacle, and give rise to paraphases and reproductive 
organs (/7gs. 27, 28, 29). The mucilaginous remains of the 
decayed cells for a time fill the cavity, or protrude from its 
mouth, or close the mouth as a stopper. The diagrams, /7ys. 
18, 20, 22, 24, 26, corresponding respectively to /7gs. 77, 79, 
21, 23, 25, illustrate how it is possible to explain the develop- 
ment of the conceptacle without using Bower’s central, persist- 
ing, basal cell theory. It is not probable that the development 
of the conceptacle in P. /fasizgzata is different from that in the 
closely related plants which he describes. Since this work by 
Bower is the principal reference we have on the development 
of the conceptacle in the Fucacez, and is generally quoted, it 
would be profitable for others to repeat these investigations. 
Finally the disintegration stops, a healthy surface layer of 
cells then lines the cavity and the dead and mucilaginous cells 
are cast off into the cavity. Meanwhile the unaffected epi- 
dermal cells continue to divide and form their basal cells which 
pass into the cortex. This new cortical growth stops abruptly 
at the conceptacle. In this way the cavity is deepened and a 
