242 BOTANICAL GAZETTE [MARCH 
What may be called the reciprocal cultivation of a single species 
has not yet been attended with success. It is more difficult to 
raise carposporelings to maturity than tetrasporelings, for the 
reason that tetrasporic plants are usually late in fruiting, while 
sexual individuals may be expected to produce reproductive bodies 
in 3-5 weeks. The experiments in their present status show, how- 
ever, that in Griffithsia and Dasya the tetraspores actually do pro- 
duce sexual plants, and only these, and that in Polysiphonia 
violacea carpospores produce only tetrasporic plants. The results 
of the experiments go to show, therefore, that the conclusions 
drawn from cytological evidence are valid, and that alternation of 
sexual and tetrasporic plants in the Florideae is now an observed 
fact. 
In conclusion, it is a pleasure to acknowledge my indebtedness 
to the friends who have assisted me in various ways in the progress 
of this work, particularly Professor Gro. T. Moore, Dr. ERNst 
A. Bessey, Mr. H. WasteNEys, and the officers of the Supply 
Department of the Marine Biological Laboratory. 
Summary 
1. There is no evidence that the double number of chromosomes 
in the carpospores imparts greater vigor of growth as compared 
with the single number of the tetraspores. 
2. From the carpospores of Polysiphonia violacea 6 tetrasporic 
plants were obtained, and none sexual. 
3. From the tetraspores of Griffithsia Bornetiana 60 sexual 
individuals were produced, and none tetrasporic. 
4. From the tetraspores of Dasya elegans 149 sexual plants were 
secured, and none tetrasporic. 
5. Tetraspores from a single individual produced male and 
female plants in approximately equal numbers in Griffithsia. The 
preponderance of males in Dasya is explained by the early fruiting 
of these as compared with the females. 
RANDOLFH-MACON COLLEGE, 
ASHLAND, VIRGINIA 
