194 CYSTOSPEKME.E. 



founded upon a partial, imperfect, and often inaccurate know- 

 ledge, and therefore not admissible. If any of the older 

 terms should be retained for the genus Vesiculifera, it should 

 be by right of priority, Conferva, for this genus hitherto 

 has been made to embrace various species of Vesiculifera, as 

 well as certainly a heterogeneous mass of other productions ; 

 but it seems to me that this genus ought to be abolished 

 altogether, and that the term Conferva should be used in a 

 more extended sense, and applied generally to any species of 

 the confervoid Alace, in the same manner as the word zoo- 

 phyte is now used. Kiitzing, in his " Phycologia Generalis," 

 confines the genus Conferva to certain species of Sphceroplea, 

 and to the marine species of Conferva, with simple filaments, 

 such as Conf. cerea and its allies. Next to Conferva, Prolifera 



and who observes that the Zoocarpea of Nees of Esenbeck, " Nov. Act. 

 Nat. Cur." an. 1813, p. 517., is the same genus. The same author 

 thinks that the greater part of the Prolifera of Vaucher, also the CEdo- 

 gonium of Link, ought to constitute part of the genus Tiresias. Of 

 Tiresias, Bory gives the following description : ' Filaments cylindrical, 

 the interior tube filled with green colouring matter, in which are de- 

 veloped hyaline corpuscles which separate from the filaments. This 

 colouring matter ends by becoming agglomerated in each cell into a 

 sphere or zoocarpe, of appearance similar to the gemma? of the Con- 

 jugate, and inert up to the moment when rupturing the cell by its 

 developement, and, putting itself in contact with the surrounding fluid, 

 it commences to move itself in different directions, and finishes,by swim- 

 ming freely about, leaving all broken and transparent as water the tube 

 which produced it.' The Conferva bipartite of Dillwyn is certainly a 

 species of Tiresias, in the vegetable condition of which the Cercaria 

 podura and viridis of Miiller are the Zoocarpes, which we have seen 

 after a certain period of liberty fix themselves by their divided extremities 

 upon the remains of vegetables, or even upon the filaments of other 

 Tiresias, and elongate themselves into a confervoid vegetable. This 

 state of elongation has been well seen and figured by Le Clerc, in his 

 excellent memoir on the Prolifera of Vaucher, as well as by Dillwyn 

 upon his Conferva genuflexa. It is surprising that these skilful naturalists 

 had not detected the metamorphoses of the Enchalis into that which they 

 call Conferva." 



Both Bory and M. Leon le Clerc are in error in supposing that they 

 had witnessed the developement of the large oval or spherical bodies 

 formed by the concentration of the endochrome of two cells : what the 

 latter represents are undoubtedly the zoospores in different stages of 

 growth. 



