Ch rooeoecacese 



41 



exceptions they are provided with a copious mucous covering. In some the cells divide 

 in every direction of space, producing an irregular colony, often of large size (Apkanocapsa, 

 Olceocapsa, Microcystis, etc.). In others the cells divide only in two directions in the same 

 plane, giving rise to a tabular colony (Merismopedia ; fig. 26, B and (7) ; and in others cell 

 division takes place in one direction only (Synechococcus, Gloeot/iece). In the genus 

 Tetrapedia (fig. 26 D] the cells are compressed and very symmetrical. In Chroococcus 

 (fig. 25) the mucous coats of the cells are often very firm and lamellose, and in Olceocapsa 

 (fig. 2 B) the inner integuments often contain red, orange, or violet pigments. The largest 

 colonies are macroscopic and may contain many thousands of cells, as in Aphanothece 

 prasina. In Coelospheerium, Gomphosph&ria and Merismopedia the colonies are of limited 

 size and definite shape, and in the two first-named genera a kind of budding takes place 

 by means of which a new colony is developed from the side of the old one, ultimately 

 becoming separated from it. 



A 





rfti 



P- 



D 



Fig. 25. A, Chroococcus f/ifiaiiti'us W. West. 

 B, Chi: turyidus (Kiitz.) Niig. C and D, Chr. 

 schizodermaticus W. West. All x 450. 



Fig. 2G. A, Dactylococcopsis montana W. & 

 G. S. West. B, Merismopedia glauca 

 (Ehrenb.) Nag. C, M. elegans A. Br. D, 

 Tctrapeditt lieinschiana Arch. All x 450. 



Fam. Chamaesiphonacese. A family of epiphytes in which the cells are generally 

 clustered in dense masses around the filaments of larger Algee (fig. 27). The cells may be 

 ovoid, pyrifortn, or cylindrical, and there is always a distinction between base and apex. 



Fig. 27. Chamsesiphon iiicrustann Grim, epiphytic on a filament of Rhizodonium. x 416. 



Reproduction occurs by the formation of gonidia which are successively cut off from the 

 upper part of the mother-cell (Chamsesiphon), or produced by the division of the contents 

 of the mother-cell by three or more sets of division-planes (Xenococcus, Hyella, Dermo- 

 carpa). 



Order II. HORMOGONE.E. Includes all the filamentous Myxophycese. 

 The filaments consist of a simple row of cells, very rarely naked, and usually 



