34 Vol. XLIII., Art. 1.— K. Yendo : 



both surfaces equally rich, and that in one and the same species 

 found either in shade or in light, the hairs show no difference in 

 their number and size. 



As mentioned above, the hairs in the Pharophj'Ceae make their 

 appearance at a very early stage of development of the frond. In 

 some member they are persistent, though the cells composing thorn 

 are constantly renewed by the basipetal growth ; in others, they 

 are present while the frond is not fully matured or is in an em- 

 bryonal stage. In Homœostroma, as above observed, there are a large 

 number of isolated hairs on the margins of the embryonal blade ; 

 they drop off as the blade grows and the tufts of hairs appear on 

 the surface of the blade (Plate XIX, fig. 12). The renewal of the 

 hairs and their shedding in the adult fronds are ample proof that 

 the hairs are not directly related to the reproduction. In a dilute 

 solution of hfe-staining material (for instance, 0.1%" aqueous anilin 

 blue in sea-water) the liairs absorb the colouring matter without 

 plasmolysis taking place in the cells while the epidermal cells take 

 in no trace of it. There may be no direct proof that the hairs 

 of the Phœophycea? are absorptive organ, but there is nothing 

 against the view, so far as I am aware, in explaining them as 

 adapted to it.^) 



Whatever it may be in other families, the hair-tufts in the 

 Laminariaceous frond can safely be regarded as a sort of absorp- 

 tive organ. The appearance of the hairs on the frond begins at 

 an early stage of development. 2) The hairs are in a most vigorous 

 state of growth just before the formation of the sori. When the 

 plant has attained full maturity, the liairs are mostly broken off, 



1) Reinke : Kenntniss der Tauge, p. 3'21. 



\ViLLE : Beitrage z. physiol. An.at der Lamin., p. 39. 



2) Mukray: Phycol. Memoirs, X. 

 Yendo : Development of Costaria, etc. 



