282 University of California Publications in Botany [Vol. 8 



FAMILY 11. ULOTRICHACEAE borzi 



Filament simple, or very rarely branched, fixed to the substratum' 

 by a usually specialized basal cell; cells in a single series, or double 

 by concrescence, uninucleate, with a single complete or broken annular 

 chromatophore having one to several pyrenoids; multiplication by 

 fragmentation, akinetes, or aplanospores ; zoospores 2- 4-ciliated; iso- 

 gametes 2-ciliated. 



Borzi, Studi Algologici, 1883, p. 25 {" Ulothriciaceae" sic!) (in 

 part) ; Blackman and Tansley, Class. Green Algae, 1902, p. 137. 

 Ulothrichme Kuetzing, Phyc. Gen., 1843, p. 251. 



The Ulotrichaceae was first designated as a family by Kuetzing 

 (loc. cit.). The name in its present form was given by Borzi [loc. 

 cit.) although the orthography was incorrect. The contents of Borzi 's 

 family was greater than used later by Blackman and Tansley {loc. 

 cit.) whose idea we follow. The majority of the Ulotrichales are 

 branched, but there are some with simple filaments and these are all 

 contained in the Ulotrichaceae. Very few of the members of this 

 family show any branching at all, and when they do it is slight com- 

 pared with that of the members of the Chaetophoraceae or of the 

 Trentepohliaceae. The great majority of the species of the Ulotricha- 

 ceae are inhabitants of fresh waters but a few species of Ulothrix are 

 marine. 



24. Ulothrix Kuetz. 



Filaments simple or rarely branched, of a single series of uni- 

 nucleate cells, all similar, and, with the exception of the attached 

 basal cell, capable of division and of producing spores ; chromatophore 

 band-shaped, with one or more pyrenoids; asexual reproduction by 

 aplanospores and akinetes, also by 4-ciliated zoospores, with red 

 stigma, formed 1-4 in a cell, germinating immediately; sexual repro- 

 duction by 2-ciliated gametes formed 8 or more in a cell, germinating 

 after conjugation ; external conditions may induce many modifications 

 of the normal process ; akinetes may be formed, ultimately producing 

 zoospores ; filaments may break up into individual cells, and these 

 by copious formation of gelatine pass into a Palmella or a Gloeocysiis 

 condition. 



Kuetzing, A:igolog. Mitth., 1833, p. 517. 



The genus Ulothrix contains both fresh water and marine species 

 and is to be distinguished from the genera Hormiscia and Chaeto- 

 morpha of the Cladophoraceae by its uninucleate cells. The pyrenoids. 



