Tribonema 181 



Microspora amoena forma thermalis Tild. Bot. Gaz. 25 : 92. 

 //. 8.f. 12. 1898. 



The author remarks : " It is difficult to decide whether this 

 plant should be classed as a Conferva or a Microspora, as the 

 structure of the chloroplastids could not be made out." That this 

 form having a diameter of 11—14/^ should be associated with a 

 species ranging from 20-24/*, in a genus of such fine distinctions 

 as Microspora, is a manifest absurdity. The form should have 

 been "placed provisionally" among doubtful forms in the discov- 

 erer's herbarium, until its essential character could be determined. 



Microspora Weedii Tild. Bot. Gaz. 25 : 93. pi. 8. f ij. 

 1898; Am. Alg.. 2 j 5. 



The figure furnishes a strong support to the suspicion that the 

 author has no adequate conception of the difference between 

 Microspora and Tribonema ; the chromatophores certainly have 

 the appearance of the latter. No satisfactory conclusion can be 

 drawn from the poor specimens distributed. 



IV. TRIBONEMA Derbes & Solier, Mem. sur Physiol. Alg 



18. 1856 



Co7iferva Lagerheim, Flora, 72 : 194-209. 1889. Not Con- 

 ferva Linn. Sp. PL 1164. 1753. 



Filaments at first attached by a special basal cell, later floating. 

 Chromatophores disk-shaped, yellowish-green, without starch, but 

 producing oil, two or several in a cell. Cell-wall thin, formed by 

 deposition of layers composed largely of pectic acid with little 

 cellulose. For the dispersal of the zoospores, the cells pull apart 

 from the middle, so that H-shaped sections are left. 



Asexual reproduction through zoospores, produced to the 

 number of one to four in each cell ; they are destitute of a red 

 eye-spot, furnished with two cilia, one of which is short and re- 

 flexed. 



Inhabitants of fresh water. Type T. bombycinum Derb. & Sol. 

 [Etym. 7 t oi t 3o£, worn, and vijfm, filament.] 



The name Conferva is very ancient, going back to the time of 

 Pliny. As a modern generic name it has received most varied 

 treatment, and covered at different times very diverse groups of 

 plants. 



Under this name Linnaeus included a very large part of the 



