IV. The young vegetative plants may become converted 



into hypnosporangia directly if the conditions are 



unsuitable for either of the above. 



The zoospores produced in II. from the young and 



immature plants may differ slightly in their subsequent 



development from those produced in the ordinary way. 



A. If placed on ordinary damp earth or sand, they 



produce only small plants with branched rhizoids — 

 ordinary zoosporangia. 



B. On clay or slime they develop into the ordinary 



vegetative plants. 



c. If kept in water they do not develop at all, and 

 if spores which have already come to rest are 

 brought into water they surround themselves with 

 a thick membrane and remain in this condition for 

 months. If they are placed on damp clay again 

 the cells escape from their thick membranes and 

 develop into much branched vegetative plants. 



Sexual Reproduction. 

 According to Rostafinski and Woronin, sexual repro- 

 duction takes place by the pairing of motile biciliate cells, 

 but Klebs has recently shown, however, that there are 

 probably two organisms involved in this life history,* and 

 that the sexual forms do not belong to Botrydiiim. 



Localities and Nomenclature. 



The first notice of the plant is given by Rayf in 

 "Synopsis methodica stirpium Britannicarum. Londin. 

 1690. III., p. 70 and 41," who refers to it as "Lichen- 

 oides fungiforme, capitulis vel vesiculis sphaericis aqueo 

 humore repletis." :|: Since then it has been described under 

 several different names. The name Botrydium was given 

 to the genus in 1815 by Wallroth, and in 1830 the plant 

 was described as Botrydium granulatum by Greville. 



* Die Bedingungren der Fortpflanzung bei Einigen Algen und Pilzen. Jena, 1896. 



t See Rostafinski and Woronin loc. cit. 



i Lichen like fungus form, with spherical heads or vesicles full of aqueous 

 humour. 



