172 



THE AMERICAN MONTHLY 



[September, 



Ulothrix. In the former the cells 

 are usually longer in proportion to 

 diameter, more robust, and the con- 

 tents more granular. In Ulothrix the 

 cells are rarely longer than their di- 

 ameter, the cell-walls thin, contents 

 effused. 



The formation of macrozoospores 

 is very readily observed in this genus : 

 it is only necessary to place the fila- 

 ments in a saucer with water over 

 night and examine them the next 

 morning, when the zoospores will 

 probably be set free.] 



57. Genus Conferva Kirchner. 



Simple series of cells, like Ulo- 

 thrix ; only microzoospores observed, 

 but no copulation of them. They 

 are formed in great number in a 

 mother-cell, and escape through a 

 circular opening in the wall. 



[The genus as thus formed in- 

 cludes Conferva Link and Micro- 

 spora Thuret. This union of the 

 two genera is to be commended for 

 the present at least ; for it is practi- 

 cally impossible to distinguish be- 

 tween them except by the generic 

 character of Conferva ' propagation 

 unknown,' while Microspora pro- 

 duces zoospores in all its cells. It is 

 stated by Wille that resting-spores 

 are produced in the genus Conferva^ 

 \vhich probably produce zoospores 

 when they germinate. Until these 

 observations receive further confirma- 

 tion it seems proper to retain the 

 genus as it is. Conferva Link in- 

 cludes usually slender filaments, with 

 rather diffused and granular pale cell- 

 contents. In Microspora , on the 

 other hand, the cells are usually more 

 turgid, the color more pronounced, 

 and the contents have a tendency to 

 contract toward the centre, finally 

 producing numerous zoospores. 



This genus also includes a pecu- 

 liar form, Psichohortniiim Kiitzing, 

 which is especially characterized by 

 incrustations of calcareous or ferru- 

 ginous matter.] 



58. Genus Schizogoniiim Kiit- 



^^ing; 



Filaments like Ulothrix^ with 



rather thick cell-w^alls, growing side 

 by side in a common gelatinous enve- 

 lope, forming more or less broad 

 bands. In moist places, aerial. 



[It is doubtful if this genus is a 

 good one. It is supposed that Schi- 

 zogoniumx^ a condition of Ulothrix r\ 



59. Genus Chcetomorpha Kiitzing. 

 Filaments thick walled, distinctly 



lamellose, cartilaginous, with rhizoid 

 attachment ; cells before division 

 equal in length or longer than the 

 diameter, after division shorter than 

 the diameter ; basal cell longer than 

 the others ; cell-contents green, finely 

 granulate with a few starch grains, 

 parietal in old cells. 



[Most of the species are marine. 

 This genus closely resembles Clado- 

 phora^ and only differs from it in be- 

 ing unbranched.] 



B. Cladophorin^. Group 2. 

 a. Chcetophorece. Sub-group i . 

 «. Filaments in gelatinous sheaths, 



with rhizoids. 



Synopsis of Genera. 



Endophytic. Filaments irregularly 

 branched, with bristles. 



Chceto/ienia, 60. 

 Main filament large, with lateral fas- 

 cicles of smaller l)ranches. 



Draparnaldia., 61. 

 Branches like the main stem ; chloro- 

 phvll in transverse bands. 



Stigeocloniuniy 62. 

 Filaments branched, radiating, in ge- 

 latinous or hard hyaline envelope 

 sjDherical, or in a ffat laver. 



Chcetophora^ 63. 



60. Genus Chcvtone/na Nowa- 

 kowski. 



Endophytic. Filaments thread- 

 like, irregularl}' branched, with 

 spreading branches, usually at right- 

 angles, most cells bearing one or sev- 

 eral terminal or median bristles, 

 somewhat swollen at the base. 



Multiplication by breaking up of 

 the branches : propagation by zoo- 

 spores formed from the entire con- 

 tents of the swollen cells at the ends 

 or the middle of the branches, or after 

 previous division into two or four 



