SEXUAL REPRODUCTION IN CLOSTERIUM MONILIFERUM AND CLOSTERIUM EHRENBERGII(1).

Sexual reproduction in C. moniliferum is described for the first time. The morphology of conjugation is quite like that of C. ehrenbergii. Homothallic strains of both species usually produce single zygospores between daughter cells that have just divided. However, 2 homothallic clones of C. moniliferum form twin zygospores between conjugants which have paired before division and conjugation. This has not been observed in C. ehrenbergii. Heterothallic strains of both species form twin zygospores in the same manner. Heterotfiallisrn seems a well-established feature in both species. Germination and the survival of 2 products of meiosis arc typical of other desmids which have been investigated.