OSCILLATORIA. 245 



Upon the reproduction of this family, and some others 

 which follow, no very precise observations appear to have 

 been made. Vaucher remarking the ease with which the cells 

 or " rings " separated from each other, supposed them to be 

 multiplied by means of these. This separation, however, is 

 probably merely to be regarded as a preparatory step, the 

 true reproduction being by means of zoospores. 



Gerod Chantrans * makes some observations upon the re- 

 production of the Oscillatorice. He states that when an 

 Oscillatoria has reached its complete developement, it emits 

 from its cells a granulated powder, each grain of which 

 increases insensibly until finally it becomes developed into 

 a perfect plant. In this account, Gerod Chantrans has not 

 swerved far from the truth. 



The species of this family are found under very different 

 circumstances ; upon the moist earth, in stagnant, still, and 

 running waters; in medicinal waters, and in such as are 

 absolutely hot and almost boiling. They are, with very few 

 exceptions, highly mucous to the touch, and in some kinds 

 the filaments are imbedded in a mucous nidus. 



The brilliancy of their colours has been noticed. The 

 tints are various, shades of bright and beautiful greens, many 

 presenting a metallic or aeruginous cast, of violet, purple, 

 dark brown and glossy black. 



No description of a species can be considered perfect, un- 

 less it be taken from an examination of specimens, both in 

 the recent and dried state, the characters not being identical 

 in these conditions. 



A monograph on this family, the result of two or three 

 years' patient and careful observation, is much needed. 



29. OSCILLATORIA. 



Char. Filaments simple, even, elastic, closely striated, and often 

 lying in a mucous matrix. 



Derivation. From oscillo, to vibrate. 



* Recberches Chimiques et Microscopiques sur les Conferves, &c. 

 Paris, an x. 



K 3 



