240 BOTANICAL GAZETTE [MARCH 
than usual, and the plants seemed to be stunted. The main 
branches ended much more abruptly than is common in this species, 
and. the development of hairs was sparse. The apices, however, 
were normal, and the plants still growing. All the smaller indi- 
viduals, 23 in number, were found to be sterile, but 6, comprising 
the largest specimens, bore tetraspores normally and abundantly. 
On neighboring shells, which were examined very carefully as 
controls, no P. violacea was found. The only contaminating species 
were P. variegata in great numbers, Champia parvula (averaging 
3 individuals to each shell), and Dasya elegans (2 per shell). It may 
be remarked parenthetically that P. violacea and P. variegata are 
species that are quite distinct, and easily and surely recognizable. 
In this experiment, carpospores were found to produce tetra- 
sporic plants, and no sexual individuals. 
IV. Griffithsia Bornetiana.—Carpospores sown July 18, 1910, 
transferred to Spindle Ledge July 19, shells collected August 12. 
The stand of Griffithsia was found to be unusually good, the shells 
resembling miniature lawns on which Griffithsia was the grass. 
The individuals were so closely appressed and interwoven at the 
base that it was impossible to ascertain the exact number, which 
must, however, have reached into the hundreds. The largest were 
about 2 cm. long, a size at which sexual individuals fruit fairly 
abundantly, but all were sterile. 
Tetraspores sown July 2, transferred to Spindle Ledge July 18, 
1910, shells collected August 10. The maximum length attained 
was 1.5 cm., and the average 0.75 cm. Numerous very small 
sterile individuals were found. Of those specimens which had 
attained a length of 1.0 cm., 23 showed developing sexual organs, 
and 7 were sterile. Of the sexual plants, 12 were male and 11 
female. Neighboring shells used as controls were destitute of 
Griffithsia. The results of this experiment were confirmed by 
cultures made in 1911. Tetraspores from a single plant were 
sown July 15, transferred to piles at Little Harbor July 18, shells 
collected August 14. The largest individuals were stocky, bushy 
plants 3 cm. long, and all were well developed, there being little 
crowding with the resulting production of dwarfed specimens. 
From one shell 45 individuals were obtained, of which 8 were sterile, 
