TJIE FUGACES OF .JAPAN. 157 



luiry growth uf abiiüriiial branches which start out tVoin tlic 

 surface of an internode of the filiform segment. We could never 

 Ihul any segment in a normal filiform frond dilata ted or com- 

 l)lanated to such a degree as is found in ii foliose frond ; nor 

 could we lind any of the segments of the foliose brunch narrowed 

 to u cylindrical or terete one, except the basal portion which is 

 inserted in the filiform segment. The point of insertion is more 

 or less intumesced, which is probably never met with in the case 

 of ordinary ramification (PI. II, fig. 2-4). After carefully study- 

 ing the nature of this foliose branch I have arrived at the con- 

 clusion that the abnormal branch was due to a parasitic organism 

 {/SirejHothrix-Vike) invested in the frond. 



The segments in the middle or the upper portion are often 

 verruculose instead of smooth. By cutting these portions crosswise 

 we find small ovate pits, in sha2:>e apparently the conceptacles of 

 a Fucaceous alga. But so far as my observation extends nothing 

 that could be suspected to be the reproductive cells of the pre- 

 sent plant could be found in them. Nor could there be found 

 any single hair growing from them. A large number of the 

 pits, if not all, belong to the parasite. 



Structure of the frond. The frond is constructed essentially 

 of t\\'o })arts, the medulla and the cortex. The medullary por- 

 tion is composed of hypheal cells much entangled with one 

 another so as to form a compact and elastic tissue. The cortical 

 part is built up of rows of cubical cells disposed anticlinally. 

 They are connected with the hypheal cells by the innermost ones 

 which are nuicli larger and more spherical than the peripheral 

 ones. The cubical ones are rich in brownish chromatophores 

 which give the frond a dark olive colour when fresh. 



In the middle portions of the frond we find two sorts of the 



