270 
dividing cover cells similar to that pointed out for the articulated fronds and for 
Lithothamnion by Sorms (Corall., p. 27 and 29). The cells of the hypothallium 
and those of the inner perithallium were, in a specimen collected in July, filled 
ı with starch grains, while the cells of the outer 
perithallium showed numerous disc-shaped chrom- 
atophores and a single nucleus. 
The articulated fronds are connected with the 
erust by a geniculum. The ramification is mono- 
podial, in the typical form pinnate. The branches 
usually arise near the growing point. At an early 
stage three (or more) small protuberances are seen 
at the upper end of the last joint, the middlemost 
of which develops in continuation of the axis. This 
Fig. 193. has been interpreted as trichotomy, or polychotomy 
Corallina officinalis. Border of basal crust (Kny 1872, Sp. 704, Sous 1881, p. 30); I think, 
in vertical section. 39:1. - 
however, with Macnus 1872, p. 721, that there is 
no reason for this interpretation, and that the middlemost outgrowth must be regarded 
as the principal axis, the others as lateral branches. In f. typica each joint bears two 
opposite branches, all in the same plane, having for the most part a limited growth, 
being “pinnulæ”, but there is no distinct difference between the pinnulæ and the 
longer branches with continual growth. It frequently happens, however, that some 
joints produce more than two branches; 6 branches are not rarely met with and 
I have found up to 10 lateral branches placed in the same plane on the upper 
border of a much flattened joint (fig. 194 A). More rarely the supernumerary branches 
are given off in different directions at the same level, being thus verticillate (fig. 
194 B, Plate IV fig.5); in a specimen from Frederikshavn, a whorl of 8 pinnulæ was 
found on a joint. It may happen also otherwise, 
that normal branches are exceptionally given off 
in a direction diverging from the ordinary plane 
of ramification. The joints bearing a great number 
of branches occur principally in the upper part of 
the shoots produced in a period of growth. Be- 
sides the normal branches, adventitious ones occur, 
though rather rarely (Comp. Soins 1, c. p.29). Their 
position is less regular than that of the normal 
branches, and they are usually given off from the 
under part of the joints. 
Fig. 194. 
Corallina officinalis. A, seriate branches 
While in the f. éypica every joint bears usually Placed on the border ofa joint. B, upper part 
two opposite branches, other specimens, especially nd So ee 
those growing in deeper water, are less branched, a greater or lesser number of 
joints bearing no branches, or only one. In these specimens the joints are cylin- 
drical or nearly so, while the joints of the much branched forms are usually more 
