A biological study of Durvillaea antarctica (Chamisso) Hariot and D ...

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{c}
The basic cellular arrangement of all species is that of a
rneristoderm, an outer and inner cortex and a medulla. The
mer istode:CI"ll and outer cortex appeaY.:'st~O be very similar in aU,
species, bu't as Naylor (1953) pointed out, there a,~e :;;pecific
differences in the composition of the inner cortex and the medulla.
In the lamina the cell walls of the inner cortical cells may
be very swollen and grea,tly gelat:ini.sed .. so that t.h(';! irmer cortex
is very open structuxed with widely spaced, irregularly shaped (often
star shaped) protoplas'ts in what appears to be a gelatinous matrix.
the cell 1tJalls may be thin and only slightly
so tha t 'the inner cortex has a pseudoparenchyma'i:o llS appearance. The
walls of medullary hyphae may be thickly gela.tinous, in which case
the medulla has a loose structure; or they may be only slightly
gelatinized, whereupon the medulla is compact with little space between
the protoplastso In young specimens of all species, the medulla
largely consists of hyphae running parallel to the plane of flati~ening,
Mos t run longi tudinalJ.y; and across the \1ide expanse of the blade or
thong (F i9 . 3. 10) . I t may be compact and uniform throughout such
as in Fig. 3.7, with the hyphae running in straight: lines; or there
may b~ innumerable small spaces (not honeycomb cells) between a mass
of mOY.'e inter'wove n hyphae such as in Fig. 3. 6c I d" l'I.,o:!.'e impol.:' t.an'tly ,
there may, or may not be a central ~one of very loosely ini:erweaving,
highly branched hyphae which run in all directions; often at right
angles to the plane of flattening (Fig_ 3.5a,bj 3.6a.). 'l'his is an
incipien't stage in the formation of' honeycomb tissue, evident long
before there is CI,ny external sign of honeycombing.
In the stipe the protoplast:;; of "i;,he innel' cm:tiCrll cells may
be greatly elongated radially