Branch I— PROTOPHYTA. 



Uni- or multicellular plants, single or aggregated into loose clusters, or mechanically 

 united into hlaments, often provided with a thick membrane or sheath; filaments 

 or clusters often aggregated into a thailus; true nucleus absent; color general'; aerugi 

 nous through various shades of red and yellow, but never chlorophyll green; asex ial repro 

 duction typical, by cell-division; sexual reproduction wanting. 



In some genera variously modified cells, called spores, are present, and in others 

 peculiarly colored cells, called heterocysts. Both sometimes occur in the same individual 



Fresh water or marine algae floating freely, or attached to a substratum, or rarely ter 

 restrial. Chiefly holophytes, but one family, the Bacteriaceae, typically hysterophytio. 



In the more primitive forms propagation takes place by means of fission, the result 

 ing cells continuing as independent plants. In others t lie resulting cells p. -main in loose 

 clusters, attached by mutual compression or imbedded in a gelatinous matrix, or in the 

 higher forms united into a multicellular filament. 



It is probable that the Protophytes and the chlorophyll-bearing algae have developed 

 in different directions from the same point. Chroococcus and Gloeocapsa on the one hand, 

 and Protococcus and Palmetto, on the other, represent the most primitive of the respective 

 groups. Nothing definite is known as to the relationship of these forms. 



Class I.— SCHIZOPIIYCEAE. 



Characters of the Branch. 



SYNOPSIS. 



Order l.-CYSTIPHORAE.- Cells free and simple, never in filaments. 



Fam.— Chrooeoecaceae.— Characters of the order. 



Order 2.— tfEJIATOGENEAE.-Cells iu filaments. 



Fam.— Ifostocaeeae.— Filaments simple, moniliform, heterocysl present 



Fam.— Oscillariaeeae.— Filaments simple, heterocysl wanting. 



Fam.— Scytonemaeeae.— Filaments moniliform, sometimes pseo loramose, n< 



cyst present. 

 Fam.— Kivulariaceae. Filaments tapering to a usually setiform apex, netero 



cyst intercalated or basal. 

 Fam.— Baeteriareae. Parasites or saprophytes, mostly unicellular. 



Order 1.— CYSTIPHORAE.— Unicellular, cell9 spherical, oblong, or cylindrical, 



for the most part irregularis disposed; oells inclosed in a gelatinous 

 matrix, in families, color variable; cell division taking place in one, two 



or three directions alternately. 



