9° 
The Ohio Naturalist. 
[Vol. VII, No. 5, 
the plicae are the last portions to be eroded away and hence they 
frequently stand out as long aeuminations beyond the blade 
proper. The stipe is exceedingly short for so large a plant, sel¬ 
dom if ever exceeding 5 cm. The holdfast has no hapteres rising 
from the stipe but instead consists simply of the primitive disc, 
which becomes about 3 cm. in diameter covering thus a very 
much smaller area than the holdfast of those kelps which have 
a number of hapteres to increase the strength of their hold on the 
rocks. As in Renfrewia the surface of the primitive disc (not 
the stipe above) is subject to local secondary growth by which 
means branches are formed which pass outward and strengthen 
the holdfast. These are, however, so flat and so closely ap- 
pressed to the disc that they are not noticeable except in sections, 
(See figure of Renfrewia, Postelsia 1906: PI. 18.) 
Specimens in fruit are not easy to find at Port Renfrew dur¬ 
ing the summer season. Late in the season, however, in old 
plants may be found at the base of the lamina on both sides, 
the lanceolate fruiting patches. Proximally they may extend 
to within a millimeter of the base of the lamina following its 
margin around till its full width is attained at which point they 
suddenly narrow to the plicae up which they extend for a dis¬ 
tance of about 25 cm., making the whole sorus 40-50 cm. long. 
At its tip the fructiferous area extends much further up in the 
grooves than on the ridges of the plicae, thus forming on one 
side three and on the other two or four acuminate points 5-25 
cm. long. 
It will be of interest to compare the positions of the son in 
Cymathere and such kelps as Nereocystis. In the latter the 
gonidia are born out near the tips of the branches perhaps a 
hundred feet from the attachment of the holdfast. Instead of 
maturing in one definite short season as seems most likely to be 
the case with Cymathere, they are borne continuously from the 
time the plant becomes mature till it is torn up by "the waves. 
When liberated the zoospores must be carried long distances by 
the waves, in addition to the space they traverse by their own 
activity, before they settle down to the substratum. But in 
Cymathere, growing in relatively quiet water, they are set free 
within a few inches of the station of the parent plant and might 
be expected to settle close around it. The habit of the one would 
be most favorable for wide dispersal but only a very small pro¬ 
portion of the reproductive bodies would succeed in establishing 
themselves in favorable situations. The other would be slower 
in dispersing itself but a larger percentage of the spores would 
start favorably. These inferences are well borne out by the 
facts of the distribution of the young of the two species. Nereo¬ 
cystis, it will be recalled, thrives only in the deep water off shore 
where it is able to reach the surface with its long stipe. But on 
