10 Puf/et Sound Marine Sta. Pub. Vol. 1, No. 2 



there it absorbs the cells downward consecutively, thus growing down 

 through the filament and eating its way as it goes {Fig. 5). Sometimes 

 it grows through a cell before absorbtion has been completed. In such 

 a case the unabsorbed content forms a collar about the neck of the akinete 

 (Fig. 4), The rupture or decomposition of the sheath of the thread per- 

 mits the akinete to escape. 



The upper end of the netlike chloroplast of the akinete is dense and 

 has small meshes. Downward the meshes are larger, and the lower end 

 for 1/4 to 1/2 the length of an ordinary cell is quite clear (Figs. 4, 5). 

 The fingerlike strips of chloroplast extending into the clear end, so much 

 resemble those which extend from the lower cells into their rhizoidlike pro- 

 jections that it is believed the lower end of the akinete as it grows within 

 the old plant becomes the holdfast end of the young plant {Figs. S, 4, 5). 

 However, this point was not determined with certainty. The upper end 

 of the chloroplast has all the "ear marks" of growth {Fig. 5), and it is 

 pretty certain that this is the point from which upward elongation of the 

 chloroplast takes place. The downward elongation of the chloroplast in 

 the growing akinete seems to be due to the increase in size of the meshes 

 of the net already formed, not to any growth of the chloroplast at the 

 clearer lower end {Fig. 5). 



The gametes and zoospores were not seen in the same filament; but 

 any ordinary vegetative cell {Fig. 2) may become a zoosporeangium or a 

 gametangium. 



In the formation of zoospores the cell contents masses around 2 to 

 3 dozen centers which are first recognizable by their darker color. These 

 then break each into a spherical or hemispherical mass of zoospores 

 {Fig. 6). The zoospores are arranged with their tails toward the center. 

 The mitosis resulting in such groups of zoospores would be an interesting 

 study. 



The zoospores escape by a transverse slit in the cell wall near its 

 middle, and are like the zoospores in Hormiscia {Figs. 4 to 11). In 

 germination they draw in their cilia and tail and become more rounded. 

 When 2 or 3 cells are formed the lower cell distinctly shows the coming 

 holdfast {Fig. 16). 



The gametes are very numerous in the gametangia. They are not 

 grouped within the cell as are the zoospores {Fig. 17). In form they 

 are spherical with a short papillalike snout at the base of the cilia {Figs. 

 18, 19). At the base of this snout is a red "eye spot." There are 2 con- 

 tractile vacuoles on opposite sides of the "eye spot." The ciliate end is 

 clearer. The number of cilia is 4. This seems remarkable since the 



