10-2 



II. Observations 

 A. Filainentoiis Form. — In tlie filamentous form, individual 

 cells are cylindrical, two or three times as long as wide. The 

 cell wall is very thin ; the protoplasm spreads along the cell wall 

 as a thin layer, the central part being occupied by a large vacu- 

 ole. On one side there is a thickening of proto- 

 plasm, which sometimes reaches the other side, so 

 that the central vacuole is cut into two. The ter- 

 minal cell is somewhat different from others ; it is 

 usually longer than the rest of the cells and tapers 

 toward the tip. The terminal cell has protoplasm of 

 uniform thickness along all the walls. The' central 

 vacuole in it reaches the tip of the cell as a fine 

 canal. 



Chlorophyll granules of small size are found 

 throughout the protoplasm. 



The nucleus as a rule lies in the thickening of 

 protoplasm just mentioned. It is difficult to see 

 the nucleus in life. When stained it appears as a 

 homogeneous black body. It consists mostly of 

 chromatin. The presence of the nuclear membrane 

 is in no way demonstrable. 



Besides the nucleus there is a refringent pyrenoid 

 body embedded in protoplasm. The position of 

 this is not fixed ; sometimes it is found near the 



-O.. 



iO 



KiG. I. Fila- 

 ment of Sli^t^eo- 



cloniiitn, show- nucleus, while in other cases it lies on the side op- 



ing transforma- pQ^ji-g j-q the nucleus. Quite often it is surrounded 



tion from the pal- '^ 



mella form (two ^X ^ ^'^''^'' Space. In borax-carmme preparations on 



lower cells) to the Other hand, it remains colorless or very light 

 the filamentou.s rgj^ {],(. nucleus being stained dark red. In cell- 

 form (three upper ,. . . •, 1- • 1 ._ . • ^ 1-1 ii 



,, ?• ^, ^^ division it divides into two in a way not unlike tiie 

 cells), X iJSo. ' 



The dark bodies nucleus. 



represent the nu- Xhe first filament from the spore contains much 



clei ; the lit'hter, pj-Qfopiasm resembling that of the palmella form. 

 the pyrenoids. ' 



The vacuole develops later. At the two-ceiled 



stage the terminal cell can be distinguished from the other cells. 



The branches can be sent off from any cell, the tranvcrsc division 



taking place only at the tip. 



