iiu: i"rcA(i;.E oi' .iai'w. 1') 



the old Olios almost always liavc the basal segments reduced to 

 the ribs, and thus the fronds become caulescent. Any one who 

 has ever tried to make a collection of this species, must have 

 recognized that the young branches which have newly started 

 adventitiously from a part of a caulescent segment are short but 

 broadly winged. The size and the shape of the receptacles, too, 

 undoubtedly tend to vary in some degree according to the locality 

 of the plant. 



Along the coast of almost the whole of Hokkaido, the present 

 species may be found in greater or less quantities. The vast 

 horizontal reef in the litoral regions of Kataoka Bay, Shiraushu 

 Island, is one of the best localities for this species within our 

 boundaries. When we hunt for different forms in such a place 

 we can easily pick up a good number of modifications in the 

 external appearance of the fronds according to the season and 

 the salinity of the water in which they grow. Some of the forma? 

 will be mentioned below. But, as K.tellman has already said, 

 quite a number are applicable partly to one forma and partly to 

 another, and often show an intermediate character. The formœ 

 I mention below are by no means all we can find within our 

 boundaries and hence can not be used in the discussion of the 

 geographical distribution or of the limit of the modification of the 

 species. What I can mention here is the occurrence of Fucus 

 evanescens in our northern seas, and the extreme variability of 

 its external forms according to the habitat and the season. 



More than half of the specimens in our hands, collected 

 from the various parts of Hokkaido, are referable to /. 'per- 

 grandis Kjellm. or to /. macrocephala Kjellm. rather than to 

 any other forma. Some of them, however, have the segments 

 much narrower than any reported of the species and a few are 



