Champia parvula, Harv. from the Carpospore . 349 
bered 1, 2, 3, and 4 in these figures, as in all the other figures 
of cross-sections. 
Now it will be apparent that as the young plant grows, the 
top, which was at first small enough to be covered by the 
four cap-cells, would finally become so broad that it would 
include some of the daughter-cells derived from the four 
initial cells. 
The four initial cells become smaller in size, and as the apex 
increases in area they become slightly separated behind. This 
allows some of the cells behind to crowd in between them, 
and then they assume the functions of initial cells, and 
daughter-cells are cut off behind them. 
If one or two of the four primary initial cells are not quite so 
large as the others, they are very likely to be pushed aside by 
this crowding forward of the cells behind them, and thus the 
apex will be occupied by five or six initial cells. If the four 
primary initial cells are of equal size and are symmetrically 
arranged, the cells behind them will not be able to displace 
them, but will take up their position just behind them, but 
with their points wedged in between them. 
It is interesting in this connection to notice Berthold’s 1 
views as to the arrangement of the apical cells. He thought 
that they were always arranged in a regular manner. There 
were four initial cells at the apex ; behind this group was 
a second group consisting of four cells placed in the angles 
of the cross formed by the first group of four cells. Behind 
the second group were eight more initial cells, arranged 
between the files of segments, derived from the eight initial 
cells in front of them. Such a case might happen if the 
development were perfectly symmetrical, although usually the 
growth is irregujar, and results in there being a circle of 5-6 
initial cells at the apex. 
Fig. 11 shows the first two sections of a plant -15 mm. long. 
In this plant there are four initial cells, numbered 1, 2, 3, 4, at 
the apex. Another cell, numbered 5, by its shape and posi- 
1 G. Berthold, Beitrage zur Morphologie und Physiologie der Meeresalgen. 
Jahrbiicher f. wiss. Botanik, Bd. xiii. p. 686, 1882. 
