96 



THE AMERICAN MONTHLY 



[May, 



will proceed to consider the genera 

 known under the general name of 

 nostocs. 



V. ORDER SCHIZOSPORE^. 



Unicellular or multicellular algae, 

 in the latter case forming simple 

 or branched series of cells or fila- 

 merits, which increase only by di- 

 vision. Cell wall soft, not silic- 

 eous, usually gelatinous ; cell - con- 

 tents bluish green, blue, red, violet, 

 orange - yellow, usually without a 

 nucleus. 



No sexual organs or zoospores. 



The two families Nostochacea; and 

 Chroococcaceae are only distinguished 

 by the filamentous character of the 

 former and the separated cells of the 

 latter. 



FAMILIES. 



Unicellular. 



Chroococcaceae XHI. 

 Filamentous. 



Nostochacea XIV. 



Fawilv Xin. Chroococcace.-e. 



Unicellular in the strictest sense ; 

 after division the two daughter cells 

 separate from each otlicr. Cells sol- 

 itary or united by gelatin. 



Di^■ision in one, two, or three di- 

 rections. Resting cells (spores) ob- 

 served in a few instances. 



[It will be of interest to compare 

 the plants belonging to this family 

 with some of the Palmellaceae, which 

 closely correspond in structure, dif- 

 fering mainly in the color of the en- 

 dochrome. This may be regarded 

 as a very trivial distinction to sep- 

 arate so widel}' in the scheme of 

 classification plants otherwise so 

 closely related ; but the great visible 

 distinction between alg;e and fungi is 

 in the color of the cell-contents.] 

 Syuopsis of Genera, 

 a. Division in Three Direc- 

 tions. 



Cells spherical or angular, single, 

 or in small families. Envelopes not 

 confluent. Chroococcus., 93. 



Cells spherical, envelopes conflu- 

 ent. Aphanocapsa^ 93. 



Cells in families, the mother cell 

 forming a common envelope enclos- 

 ing the daughter cells. 



Glceocapsa^ 94. 



Families united in grape -like 

 masses. Poly cyst is., 95. 



Cells closely aggregated in solid, 

 spherical families. Microcystis^ 96. 



Cells in spherical, solid families, 

 the peripheral cells wedge-shape. 



Gonip/iosp/nvria, 97. 



b. Division at first in three 



directions, later only 

 in the two radial to the 

 surface of the sphere. 



Cells in an irregularlv lobed or 

 latticed gelatinous matrix. 



ClatJirocvstis., 9S. 

 Cells spherical, on the periphery 

 of a structurless sphere. 



Ccelosp/i cerium., 99. 



c. Division only in tw^o di- 



rections AT right an- 

 gles. 



Cells in rectangular, tabular fam- 

 ilies of 8, 16, 33, etc. 



^lerismopedia^ 100. 

 (/. Division only in one di- 

 rection. 

 Cells cvlindric, single or in series 

 of 2-4. SvnccJiococcus., lOi. 



Cells elliptic, in families enclosed 

 bv diffluent membrane of parent cell. 

 G/a/icocvstis., 102. 

 Cells elongate, in structurless gela- 

 tin. Aphanothece., 103. 

 Cells elongate, in lamellose mem- 

 branes, enclosed in a common gel- 

 atinous vesicle. Glceot/iece., 104. 

 [It will be observed that we have 

 genera named Ap/tanocapsa with 

 spherical cells, Aphanothece with 

 cvlindric cells, Gloeocapsa with 

 spherical cells, Glceothece with cyl- 

 indric cells. These distinctions are 

 easily reniembered.] 



a. Division in three direc- 

 tions. 

 92. Genus Chroococcus Niigeli. 

 Cells spherical or angular from 

 mutual pressure, single or in small 

 families, in gelatinous thallus, irreg- 

 ularly distributed, not enclosed in the 



