227 



The basal cells in the branchlets are small, nearly quadratic 

 (comp. Figs. 213 and 214), while the other cells in the rachis are 

 nearly cylindrical, a little thicker upwards where the pinnae 

 issue. The basal cell is very persistent, more or less immersed 

 in the mother cell and remains after the branchlets have died; as 

 pointed out by HowE 1 ) for A. densum so in the present species 

 also, rhizoids grow out from this cell ; adventitious, erect fila- 

 ments too arise from it. 



The cells in the rachis of the branchlets are from 20 24 ^ 

 broad and 50 150^ long or more. The pinnaa are simple 

 or ramified and generally provided 

 with a single pinnule growing out 

 mostly from the secund cell from 

 the base on the distal side of the 

 pinnae (Fig. 215). These pinnules 

 (Fig. 216 6, c, d) consist generally of 

 two to four, seldom more, cells about 

 IVa times as long as broad (long, 

 cell. = = 10 f*, lat. 13^). Nearly every- 

 one of these small pinnules carry 

 a large, oval, clear gland-cell on 

 their upper (inner) side. This is 20^ 

 long and 13 // broad. 



As to the development and 

 position of the glands the present 

 plant seems to come near to A. cm- 

 datum according to the description 

 by NESTLER 2 ), still a few small differ- 

 ences OCCUr. While in the latter Fig. 214. Antithamnion antilla- 



plant the gland-cell is in contact with num nov : fP ec - P? rt f a P lant - 



(About 80 : 1). 



3 4 cells, in my plant, as a rule, it 



abuts on to two cells, or more seldom three cells (Fig. 216 

 b, c, d). Nor have I ever in my plant seen the "stab-oder leisten- 

 formigen Bildungen" which NESTLER found in A. cruciatum; but, 

 of course, it must be remembered that I have not been able to 

 examine living material. As to the development of the gland- 

 cells I have once come across (in the very scarce material at hand) 



1 ) HOWE, M. A., The marine Algae of Peru. (Memoirs of the Torrey Bot. 

 Club, vol. XV, 1914, p. 151). 



2 ) NESTLER, A., Die Blasenzellen von Antithamnion Plumula (Ellis) Thur. 

 und Antithamnion cruciatum (Ag.) Nag. (Wissensch. Meeresunter- 

 suchungen, III. Bd., 1, 1899). 



15* 



