266 



1. Polysiphonia havanensis Mont. 



MONTAGNE. J. F. C., Cent, plant, cell. exot. nouv. (Ann. sc. nat., Bot., II. 

 Ser., t. 8, 1837, p. 352). RAMON DE LA SAGRA, Hist nat. Cuba, p. 34, tab. 5, 

 fig. 3. KUTZING, FR., Spec. Alg., p. 818; Tabulae Phycologicse, vol. XIII, t. 72, 

 fig. a d. HARVEY, Nereis Bor.-Am., II, p. 34. J. AGARDH, Spec. Alg., vol. 

 II, pars III, p. 959. 



The specimens reach a height 

 of up to 10 cms. 



This plant has four pericen- 

 tral cells, and no cortical layer is 

 present. The branches are formed 

 in connection with the trichoblasts, 

 not exactly in their axils, but push- 

 ed somewhat to the side (Fig. 261); 

 they are mostly formed on the left 

 side of the trichoblast (the katho- 

 dic side), sometimes too on the 

 right side. 



The base consists of creeping 

 filaments; these have thick walls 

 and are often rather torulose, the 

 filaments being thickest at the 

 cross-walls; f. i. one filament was 

 250 fj. at the cross-walls, but only 

 170 a in the middle between them 

 (Fig. 260). 



The segments in the creeping 

 filaments as well as in the whole 

 plant are of rather variable length, 

 sometimes shorter than their length, 

 sometimes 3 4 times longer than 

 their breadth. 



The basal filaments are fixed 

 to the substratum by means of 

 rhizoids breaking out everywhere 

 from the pericentral cells, but 

 mostly near their crosswalk (Fig. 

 260). The rhizoids have no cross- 

 walls ; they have rather thick peri- 

 pheral walls and end in an irregularly lobed disc. The cylindri- 

 cal part is about 25 (JL thick. 



Fig. 259. Polysiphonia Havanensis 

 Mont. Part of filaments with tri- 

 choblasts. (About 16:1). 



