LYNGBYA. 295 



Genus 100, CHAM^ESIPHON, A. Br. and Grun. 



Short, tubular, parasitic, aeruginous cells witli thin, color- 

 less, but distinct sheath. 



Propagation by means of one-celled gonidia. 



CHAMAESIPHON INCRUSTANS, Grim. 



Tubes short, contracted at the base, forming a short stipe ; 

 younger plants have apex closed, rounded ; later open ; 

 sheath indistinct. 



Diameter of tubes, a"5out 4 yw ; length, 16-17 yw. 







In ponds, parasitic on submerged plants. 

 Plate CC, fig. 3, young plants often thickly clustered, 

 forming an incrustation. 



CHAMAESIPHON CONFERVICOLA, A. Br. 



Tubes from the base narrow cylindrical, or sometimes 

 slightly swollen, solitary or in clusters. 



Diameter of cells, 3-4 // ; length, 25-35 /*. 

 Parasitic on larger forms of algse, ponds. 

 Plate CC, figs. 1, 2. 



Genus 101, LYNGBYA, Ag. et Thur. 



Filaments enclosed singly in a sheath, simple, or only excep- 

 tionally exhibiting the appearance of the beginning of ramifi- 

 cation where the trichonie issues from the side of the sheath ; 

 often combined, forming a membranaceous stratum. 



This genus, as it now stands, emended by Thuret, includes 

 all the plants of the genus Phormidium, Kg. ; Siphoderma, Kg. ; 

 and the sheathed forms under Lepothrix, Kg. ; Hypheotlirix, Kg. ; 

 AmphithriXj'Kg.; Leibleinia, Kg. 



Propagation takes place by means of hormogons, which slide 

 out of the sheaths ; the disc-formed cells, singly or in short 

 series divide and multiply and then develop sheaths, thus repro- 

 ducing the plant. 



Another mode appears to be that the single disc-forms pro- 

 duce gonidia from which spring Mastigonema-forms, which de- 

 velop Lyngbya filaments. Compare Plate CLXXVI, figs. 6, 7, 8, 

 and description. Forms like fig. 1, (same Plate) are of frequent 

 occurrence, parasitic on Lyngbya Wollei, probably young growths 

 of the plant. Perhaps these statements should be made with 

 some degree of hesitation. Some of the Mastigonema- forms have 

 been shown to be young conditions of different varieties of 



