334 FRESH-WATER ALG.E OF THE UNITED STATES. 



Genus 120, CHEOOCOCCUS, Naeg. 



Cells spherical or more or less angular from mutual pressure ; 

 solitary, or united in small families, without being enclosed in a 

 distinct tegument. Cell contents aeruginous or pale bluish green, 

 also yellow and orange. 



Propagation by division, alternately in three directions. 



The cells represented under this genus are more simple than 

 those of Gloeocapsa, and not so numerous. 



Eabenhorst describes 25 ; Kirchner 9, and Cooke in his British 

 Algce, has only two. They are not of rare occurrence, usually in- 

 termingled with other forms to one or the other of which they 

 are evidently related. Dr. Itzigsohn, in his superb work on the 

 Life-history of Hapalosiphon (1853), shows that Chroococcus cells 

 are closely related to this plant, and then remarks : "I have 

 observed these dimorphose Chroococcus cells associated with 

 species of Tolypothrix, and believe that all the forms described 

 as Chroococcus, are nothing more or less than spores of Nostocece.'' 



Dr. Hansgirg of the University of Prague, also, in a recent 

 paper (1885 ) of fifty pages on the Polymorphisms der Algen, shows 

 that almost all, if not every one, of the forms of the family of 

 Chroococcacea ?, Eab., including Chroococcus, Naeg. ; Gloeocapsa, 

 (Kg. ) Naeg. ; Aphanocapsa, Naeg. ; Synechococcus, Naeg. ; Gloeo- 

 thece, Naeg., etc., are closely related to more highly developed 

 forms ; that is to say most, if not all of the so-called unicellular 

 aeruginous algae, Cyanophycece. have their origin in filamentous 

 plants breaking up into single cells like those which develop 

 them. 



Dr. Hansgirg' s paper (German) commends itself as a very 

 valuable contribution to all interested in the study of the mor- 

 phology and life-history of Fresh-water Algae. 



As an illustration of the forms known as Chroococcus, several 

 species are quoted. 



CHROOCOCCUS TURGIDUS, Naeg. 



Cells spherical, oblong ellipsoid, or more or less angular 

 from compression ; single, twin, ternate, or quaternate 

 (rarely eight ) associated in families ; tegument thick, often 

 somewhat lamellate ; colorless. Cell membrane thin. Cell 

 contents primarily bright aeruginous ; later becoming 

 brownish. 



Diameter of cells, 13-25 yw. 



Syn. Protococcus turgidus, Kg. ; Haematococcus binalis, Hass. ; 

 Chroococcus multicolor atus, Wood. 



