1885.] 



MICROSCOPICAL JOURNAL. 



171 



zoids not observed, bvit in a few cases 

 copulation of two similar swarm 

 spores has been seen. The product 

 of such copulation is a zygospore 

 (isospore) which passes through a 

 resting stage, then grows and produ- 

 ces unsexual zoospores, which pro- 

 duce new plants. 



Usually propagation takes place by 

 the formation of one or numerous 

 asexual zoospores within each cell. 

 These are colorless at the front end, 

 with a red pigment spot, and 2 cilia 

 (microzoospores) or 4 cilia (macro- 

 zoospores) . Both kinds are common 

 in some genera, but only the micro- 

 zoospores can copulate. 



Resting cells of various kinds are 

 found in most genera. 



FAMILIES. 

 Filaments branched or unb ranched, 

 with or without gelatinous envelopes, 

 cells sometimes ending in long bristles. 



CONFERVACE^, VI. 



Filaments branched, upper part of 

 cells swollen, all endochrome passing 

 from the lower part into the swollen 

 portion. Pithophorace^, VII. 



Family VI . Confer vace^ . 



Branched or unbranched filaments, 

 cell-walls either delicate or thick, 

 sometimes distinctly lamellose, with 

 or without gelatinous envelopes or 

 sheaths ; terminal cells sometimes 

 ending in long bristles or hyaline 

 points. 



Propagation by macro- and micro- 

 zoospores, in some genera by resting- 

 spores. 



A. Filaments unbranched, or at 

 most with short, lateral rhizoids ; ter- 

 minal cell without hair-like termina- 

 tion. 



Zoospores of two kinds, macro- 

 zoospores with 4 cilia, microzoo- 

 spores with 2 cilia, 8 many in a 

 single cell, which may copulate, or 

 vegetate without copulating. Copu- 

 lation produces a zygospore, which 

 'grows slowly to an unicellular plant, 

 that produces a number of macrozoo- 

 spores. Other resting-spores not ob- 

 served. (Ulotrichin^). 



B. Filaments branched ; lower cells 

 converted into colorless rhizoids, ter- 

 minal cells often provided with long 

 hairs or bristles. (Cladophorin.«) . 



a. Cell- walls delicate, 2-16 zoo- 

 spores formed in one mother- 

 cell, with 4 cilia, set free by rup- 

 ture or swelling up of the mother- 

 cell. (Chvetophore^). 



b. Cell-walls thick ; zoosporesvery 

 numerous (at least 32) in one 

 cell, set free through an opening 

 in the cell-wall, with 2 or 4 cilia. 



(Cladophore^) . 



c. Spreading, flat, in a single layer 

 of cells, either leaf-like, smooth, or 

 crisped, or in the form of a hollow 

 tube. (Ulvin^) . 



A. Ulotrichin^. Group i. 

 Synopis of Genera. 

 Filaments tortuous, with short lateral 

 proliferations. Rhizoclonium^ 55* 

 Cells rarely exceeding diameter in 

 length ; walls delicate. 



Ulothrix^ 56. 



Cells longer, usually turgid, contents 



granular. Conferva., 57. 



Filaments like Ulothrix., parallel, in 



gelatinous envelope. 



Schizogonium., 58. 

 Filaments large, not branched ; walls 

 distinctly lamellose and thick. 



Chcetomorpha^ 59. 



55. Genus Rhizoclonium Kiitzing. 



Filaments like Conferva., but dis- 

 tinctly tortuous (bending back and 

 forth), with short, lateral, pointed 

 proliferations or rhizoids. 



56. Gewu^ Cnothrlx Kiitzing (ex- 

 tended) . 



Simple filaments, basal cell ex- 

 tended to a rhizoid. Macro- and 

 microzoospores, the latter copulating 

 (as observed in U. zonata) ; both set 

 free while the cell-walls swell and 

 break up. 



[The genus as thus constituted in- 

 cludes Hormiscia., Areschoug, a 

 genus usually recognized, character- 

 ized mainly by thick and robust cell- 

 walls, often distinctly lamellose. 



In the sterile condition it is difficult 

 to distinguish between Conferva and 



