Gibsmithia hawaiiensis — Doty 
459 
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FIG. I 
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CVI 
FIGS. 1-2. Gross aspects of Gibsmithia hawaiiensis (type specimen 19263). I, Whole thallus illustrating 
the rounded stem with growth rings. 2, A few of the soft gelatinous branches enlarged to show asymmetrical 
placement of the sexual sori and the superficial filaments which, in tetrasporic thalli, would bear the tetra- 
spores and seirospores. Below is shown some of the stem material of very different, almost woody, nature and 
the origins and rebranching of the ultimate branches of the thallus. 
(Ridgway, 1913). The soft, gelatinous, ultimate 
branches are lighter red in the same series or 
their bases are lighter and their apical portions 
darker. The branches are often up to 4 cm 
long, and they gradually enlarge apically until 
they are club-shaped and up to 1 cm in diam- 
eter near their tips. These ultimate branches 
rarely arise singly from the parent stem; more 
often (Fig. 2) they arise from a disk that is 
a flattened expanse of the same gelatinous na- 
ture and which divides somewhat dichoto- 
mously into the branches. 
The gelatinous branches are made up of cal- 
lithamnioid filaments (Fig. 3). The exact na- 
ture of the central axis of the thallus has not 
been determined, but the alga is believed to 
be multiaxial in structure. The major axes in 
the medulla bear, most often, opposite branches 
which seem to arise near the apical cell. Toward 
the exterior the branching of the filaments is 
pseudodichotomous, and the surface of a gela- 
tinous branch is generally covered densely, espe- 
cially toward the tip, with free tufts of such 
filaments. 
Branches of the axial filaments in the medulla 
often give rise to recurrent branches (A in 
Figs. 3-5) or rhizoids, which anastomose with 
a particular cell of another branch (Fig. 3), 
the supporting cell of the branch (Fig. 4), or 
with the next cell below in the same branch 
(Fig. 5). Pit connections appear between all 
cells concerned in these cases. In content, the 
cells of such anastomosing branches, like those 
reported and figured by Feldmann-Mazoyer 
(1940: 142, 393, fig. 48) in Pleonosporium 
horreri, are not particularly different from the 
cells of similar nearby filaments. 
Reproductive structures of three kinds have 
been found in the collections studied. These 
are interpreted as seirospores, as tetrasporangia, 
or as various stages and structures leading 
toward carpospore production. The same thal- 
lus may produce both tetraspores and seiro- 
spores, a situation I have seen in Seirospora, 
and which is reported ( Feldmann-Mazoyer, 
1940) in Dohrniella. The evidences of sexuality 
have been seen positively in only the type and 
two other collections. Unfortunately the critical 
stages involving the primary and secondary 
connecting filaments between the carpogonia 
