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284
rally occur in the conceptacles and are very persistent, I have
series of sections where neilher myself nor others have been able
lo discover a single one. I believe it is a small epiphytic alga;
on un-stained material it differs a little in colour from the sur-
rounding cells, being more greenish. The shape suggests Codiolum,
a genus of Chlorophyceae, which, however, has a solid stipe; this is
the case also with the epiphytic C. petrocelidis Kuckuck. C. Nor-
denskioldianum Kjellm. has a narrowed hollow part which tapers
into the proper stipe. I have not been able to prove the occur-
rence of starch in the preserved material, but also KJELLMAN was
unsuccessful in spile of his species being a true Codiolum.
If I am right, why do we not find it in the old tissue? We can
understand that the epiphyte is unable to penetrate the mature
cortex and thus starts by infesting the meristematic region. Most
of these bodies establish themslves in the very young conceptacles
which are iniliated in the growth-zone. They are generally found
in old conceptacles as well. But traces of them must be very
difficult to discover in the old sterile corlex, which is very com-
pact and of a dark brown colour. I have observed it in almost
mature cortex tissue (fig. 3 c); this is not a place for a young
conceptacle, but sterile cortex that has nearly altained its definite
thickness. Further observations ought to be made on living
material.
The conceptacle.
According to MITCHELL and WHITTING the initial in the concept-
acle of Splachnidium is homologous with the initial in the Fucus-
conceptacle. Roe states that development is the same in both cases.
I have made the following observations. The conceptacles arise
in the growth-zone. On a small circular area the terminal cells
develop into long, persistent hairs with all the cells cylindrical
and subhyaline, differing from the other hairs. No firm cortex is
formed in the bottom, which remains very thin (fig. 4—5); as the
surrounding tissue increases in thickness, a depression results.
According to hor rapid radial division of the border cells contri-
butes new tissue to the conceptacle, but MITCHELL and WHITTING
say that the bordering hairs are older and the central ones younger.
The statement of Ror stands in opposition to her own general
statement that the initial is the centre of greatest activity. I have
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