4 
K. MI V ABE 
Chapter 2 
DESCRIPTION OF GENERA AND SPECIES 
1. Laminaria Lamoukoux 
Lamouroux, Essai, 1S13, p. 20 (pro parte ). 
Holdfast is filiform or disc-shaped. Stipe is simple, directly 
continuous to a single entire or palmately splitted blade. Blade 
is without a midrib but thickened and elevated on one surface 
longitudinally in the central portion, which is called the median 
fascia and in young blades of some species is provided with a row 
of bullations along both its sides or in other species with a smooth 
surface from the beginning. Zoosporangial sori are on the surface 
of the blade, not uniform in shape and development according to 
the species. Mucilage canals are present in both stipe and blade 
in some species but lacking entirely from the stipe in some others. 
Among the genera of the Laminariaceae, Laminaria is most 
rich in species and most valuable for practical use. According to 
the latest survey, there are about forty species of Laminaria in 
the world, of which twelve are known to occur in Hokkaido and 
vicinity. 
In classifying the Laminaria species of Hokkaido, the author 
has generally followed the system proposed by Guignard (1893). 
This French author is of opinion that some species of Laminaria 
lack mucilage canals in both stipe and blade, and for an example 
of such species he mentioned of L. angustata. However, the result 
of the present study has shown that L. angustata possesses the 
canals in the blade. However, they do not form a continuous net- 
work as in other species but are interrupted here and there so 
that a cross section of the blade may sometimes happen to show 
no canal. So a close examination of the other three exotic species, 
which Guignard enumerated as other examples of such kind of 
species, may disclose the presence of mucilage canals as observed 
in L. angustata. If the entire absence of the canals in those species 
is proved, it should be better, the author believes, to remove them 
from the genus Laminaria. 
