232 



THE AMERICAN MONTHLY 



[December, 



[Representatives of this interesting 

 genus have been found in various 

 parts of the country ; first by Mr. 

 Wolle, near his home and in New 

 Jersey. We have it now growing in 

 an aquarium in Washington, but the 

 source of this specimen is uncertain. 



The mode of branching, and the 

 general appearance of the cells are 

 precisely like Cladophora. The pe- 

 culiar method of spore-formation is 

 distinctive.] 



b. Oospore JE. 



Oogonia and antheridia. 



After fructification the oosphere 

 produces an oospore, while the for- 

 mer becomes surrounded with a thick 

 wall and becomes a resting cell. 

 Spermatozoids are formed in differ- 

 ent cells, and are of variable form. 

 They find their way through an open- 

 ing into the oogonium, and there 

 complete the fructification by fusing 

 with the oosphere. 



In most of the members of this 

 division propagation by zoospores 

 is also observed. 



FAMILIES. 



Filamentous, confervoid, aquatic 

 or terrestrial ; rootless. 



Sph^ropleace^, VIII. 



Filamentous, aquatic, basal cell 



root-like, attached ; spores in globular 



swellings. OEdogoniace^, IX. 



Fiat, spreading, cells with bristles. 



Coleoch^tace^, X. 



JFamilyN\[l. Sph^ropleace^. 



Filamentous algae, living in water 

 or on land, green, unb ranched and 

 rootless, of conferva-like appearance. 



Propagation sexual, the vegetative 

 cells becoming sexual organs. The 

 oogonia forrri their protoplasmic con- 

 tents by balling it together into a sin- 

 gle or many oospheres, throwing out 

 a watery fluid. " In the cells destined 

 to ' produce antheridia the plasma- 

 contents divide into reddish-yellow 

 spdrmatozoids, which leave the an- 

 theridium, enter the oogonia through 

 openings in the walls, and fertilize the 

 oospheres by fusing with them. 



These become oospores surrounded 

 with a tough membrane, and their 

 green contents become colored red by 

 an oily substance. After a long time 

 they germinate, while they (in Sphce- 

 roplea) divide into 2-8 parts, which 

 leave the spore as swarm-cells (zoo- 

 spores) , and, coming to rest, give rise 

 to new filaments. 



Synopsis of Genera. 



Green spherical cells, sepai^ated, in 

 linear series, in hyaline tube. 



Cylhzdrocapsa^ 77. 



Filaments of long, cylindrical-cells, 

 with numerous, regularly spaced 

 vacuoles dividing the endochrome in- 

 to bands. Sphceroplea^ ^8. 



77. Genus Cy lin dr o c a p s'a 

 Reinsch. 



Young filaments attached, at first 

 consisting of a linear series of cells, 

 later often producing, by dividing 

 walls parallel or inclined to the long 

 axis, irregular or complex bands. 



Cells short, cylindrical, spherical, 

 or oblong, with dense, bright green 

 contents, and starch granules, and 

 thick, colorless envelope. 



The oogonia are produced in veg- 

 etable cells, which become spherical, 

 the entire contents formed into a 

 single, spherical or egg-shaped 

 oosphere. The walls of the oogonium 

 consist of 3-6 broad, colorless layers 

 (of the cell-wall) , widely separated at 

 the poles, but close laterally. 



The antheridia are produced in 

 the same filament by division of a 

 vegetative cell in 2 or 4 daughter 

 cells, not surrounded by special en- 

 velopes, in each of which 2 spindle- 

 shaped spermatozoids of yellow color 

 with a hyaline anterior portion, con- 

 taining 2 contractile vacuoles and 2 

 cilia, are formed. Escaping, these 

 make their way to the oogonium, the 

 wall of -which has opened on the 

 side, enter, and fertilize the oosphere. 

 The latter then becomes covered 

 with a double contoured membrane 

 and becomes an oospore ; the con- 

 tents change to a reddish-yellow 

 color, and a long resting period fol- 



