BOTRYDIUM. 155 



Genus 31, BOTRYDIUM, Wallr. 



Vegetative plants unicellular, multiplying by division of cells 

 and by development of zoospores. Asexual zoospores furnished 

 with one, and sexual zoospores with two cilia. Sexual isospores, 

 sometimes globular, sometimes compressed, alike capable of 

 germination, are clothed with several tuberculate thickenings. 



Rostafinski and Woromin's careful researches into this genus 

 show that this plant has various modes of multiplication. Zoo- 

 spores are produced in a fourfold way. 1. From the vegetative 

 plant ; 2. from the ordinary zoosporangia ; 3. from the root cell, 

 and 4. from the hypnosporangia. Further modes of increase 

 are ; 5, by cell division ; 6, by formation of macrospores ; 7, by 

 formation of zoospores. 



The plant possesses also fivefold resting stages : 1, of the 

 asexual zoospores laid in water for months ; 2, of the root cells ; 

 the year throughout in which they originated ; 3, of the hypno- 

 sporangia ; the year throughout in which they originated ; 4. 

 of the macrospores ; for years ; 5, of the isospores ; at least over 

 the year in which they originated. 



In dry seasons, unfavorable to development, the cell contents 

 are often scattered, and seemingly transmuted into forms which 

 have been erroneously called Protococcus coccoma; P. palustris, 

 and P. botryoides. In proper and favorable season, the same 

 cells reproduce sexual microzoospores and these again the 

 original form. 



BOTRYDIUM GRANULATUM, Linn. 



Usually gregarious, often aggregated, rarely confluent, 

 cells globose-pyriform, size of a poppy seed, or more usually 

 of a mustard seed, or larger ; leek -green, sometimes pulver- 

 ulent. 



Syn. Hydrogastrum granulatum, Rab. ; Lichenoides fungiforme, 

 Ray Syn. ; Tremella palustris, Dillen. ; Botrydium argilla- 

 ceum, Grev. ; Vaucheria radicata, Hook. ; Viva granulata, 

 Huds. 



Plate CXXXI, figs. 1, 2, cells (plants) about twice the 

 natural size ; fig. 3, two empty cells with tops fallen in ; 

 figs. 4-7, cells magnified, with the system of subterranean 

 radicles ; fig. 8, the cell contents passing down into the 

 radicles; fig. 9, the radicles developing zoospores; fig. 10, 

 cell (zoosporaugiuni) contents dividing and developing and 

 scattering microzoospores ; fig. 11, zoospores highly magni- 

 fied, sexual ; fig. 12, asexual macrospores ; fig. 13, zoospores 



