Hormiscia tetraciliata sp. nov. 



T. C. Frye, and S. M. Zeller, 

 University of Washington, Seattle. 



Growing abundantly in several localities in the region about the Puget 

 Sound Marine Station there is a plant which has always been traced to 

 the genus Hormiscia but whose species has not been so very certain, not 

 fitting exactly any one of the described species {Fig. 1). Usually it has 

 been referred to H. wormskjoldii, II. collabens, or H. incrassata. Dur- 

 ing the summer of 1914 the writers collected this species as a type for 

 class work at the Station, and found it reproducing excellently both 

 sexually and asexually. Careful study of the gametes showed that it did 

 not agree in all its characteristics even with the genus Hormiscia. A 

 thorough study of it was therefore made. 



The holdfast is like that of Hormiscia (Fig. 3). The germinating 

 spores begin at once to form a sheath about the filament, and when about 

 2 cells long the lower cell elongates pushing out 1 or 2 rhizoidlike pro- 

 jections. These extend downward breaking the sheath and almost always 

 forking at least once. The lower portion of these rhizodlike projections 

 is hyaline, not green, and the tips later are flaring so they are somewhat 

 trumpet-shaped. Meanwhile these cells just above the lower one success- 

 ively form each in the same manner one similar rhizoidlike projection. 

 Thus the lower 6 to 15 cells form the holdfast (Fig. 3). The number of 

 projections distends the sheath and more or less conceals the lower cells. 

 The elongation of the projections pushes the plant up from the surface 

 to which it is attached until the lower cell is lifted as much as 5 cell- 

 diameters from the substratum. 



When a cell of the thread dies, leaving the upper part without a 

 living connection with the lower part, the basal cells of the upper part 

 form rhizoidlike projections in the normal manner. These burst through 

 the lateral wall at the base of the lower living cell of the upper piece, 

 and growing downward on the outside of the wall, attach themselves to 

 the outside of the sheath of the upper cells of the lower piece. It will 

 thus be seen that a piece cut off from a plant will become as nearly like a 

 whole plant as the situation will permit. 



Any cell above the holdfast may form an akinete. In this process 

 the cell swells very much and absorbs the end wall below it. Not stopping 



(9) 



