44 University of California Puhlications in Botany [Vol. 8 



4. Hyella socialis S. and G. 

 Plate 2, fig. 5 



Filaments penetrating into the host, 200-300/^ long, tortuous, 

 branching dendroidally, at first cell divisions only in one plane, later 

 dividing in all directions, producing groups of cells within the original 

 sheath ; each group resulting from the divisions of a single cell in the 

 filament, becoming practically independent, similar to groups of 

 Gloeoc-apsa cells, the largest groups being nearest the surface of the 

 host; cells very angular, irregular in shape and size, 4^6/^ diam., 

 terminal penetrating cell 7-9/a long, decidedly conical ; cell walls 

 hyaline, soft; cell contents bright blue-green; gonidangia unknown. 



Growing in the stipitate portion of Iridaea minor J. Ag. in the 

 lower littoral belt. Carmel Bay, Monterey County, California, May, 

 1916. 



Setchell and Gardner, in Gardner, New Pac. Coast Alg. 11, 1918, 

 p. 443, pi. 36, fig. 5. 



The basal filaments of the plants, if present at all, cannot be thor- 

 oughly worked out with the material at hand. Further study will be 

 required to elucidate this point. The early stages of the development 

 of this species are unknown. No gonidangia were present and the 

 host plant was nearing maturity. It is possible that no gonidia are 

 developed, and that the dissolution of the sheath of the groups of 

 vegetative cells free them at the time that the host is beginning to 

 disintegrate and these vegetative cells locate on younger hosts. 



"We have placed this species in the genus Hyella on account of 

 its close similarity in some of its vegetative characters and in its 

 penetrating habit to those of H. oaespitosa B. and F. (1888), the orig- 

 inal species of the genus. They represent cell divisions as taking place 

 in all directions at the base of the erect filaments. In surface view the 

 cells arising from divisions of the cells in the basal filaments appear 

 in more or less isolated groups in their illustrations. The few cells 

 near the base of the erect filaments are less divided, and the terminal 

 cells of the erect filaments remain undivided. The erect filaments thus 

 become somewhat isolated, and clavate in form. The filaments of 

 H. soci^alis appear to be formed in the same manner although they are 

 crooked and branched. In the absence of knowledge concerning the 

 prostrate portion of the thallus, characteristic of the typical Hyella, 

 and in the absence of gonidangia, this species must remain somewhat 

 in doubt as to its generic positon. 



