Cytotaxonomical Studies on Cladophora Hutchinsiae Harv. and C. refracta Aresch., two Marine spp

Abstract

1. The present paper deals with the cytological investigations of the two marine spp. of Cladophora, C. Hutchinsiae Harv, and C. refracta Aresch. which were collected from the British sea-shores in 1956.
2. The detailed morphological characters of these two spp. have been studied. The plant material of C. Hutchinsiae Harv. fits the figure and description given by Harvey (1846-51, plate XXIV), Dillwyn (1809, plate 109) Kützing (1853-54, Tab. 87, Fig. 1). The width of its main filaments agrees with the diameters given by Hauck (1885, p. 453), DeToni (1889 p. 314), Setchell and Gardner (1920, p. 213) Collins (1928 p. 265) and Newton (1931 p. 82).
3. The diameter of main filaments and ramuli of C. refracta Aresch. agrees with Newton (1931, p. 85); but the cells of its main filaments are found sometimes up to 6 times as long broad.
4. Quadriflagellate zoospores and biflagellate gametes have been observed to be produced from similar but separate plants of C. Hutchinsiae Harv. Both types of swarmers vary in shape and size with those of the zoospores and gametes that have been observed by the author (1963) in C. flexauosa Harv.
5. Biflagellate gametes have been observed to be produced from C. refracta Aresch. The gametes of this plant also vary in shape and size of the gametes of C. Hutchinsiac Harv. and that of C. flexuosa Harv.
6. Stages of meiosis and mitosis have been studied in C. Hutchinsiae Harv. If meiosis precedes zoospore formation, this species appears to be a diploid one and possesses a life cycle showing isomorphic alternation of generation as was observed by the authors (1963) in C. flexuosa. C. refracta Aresch. under investigation appears to be a haploid species in which the production of gametes only have been observed.
7. In C. Hutchinsiae, the number of chromosomes has been estimated 24 from the mitotic metaphase which is the diploid number of this species. The number of 12 bivalents has been estimated during meiosis. In C. refracta 12 chromosomes have been counted from the mitotic metaphase, this being the haploid number for this species.
8. The chromosomes show localised median and sub-median centromeres like most higher plants. Each meiotic bivalent shows either one or two chiasmata and the meiotic divisions do not differ essentially in its particulars from those in the higher plants.
9. The present two spp. C. Hutchinsiae Harv. and C. refracta Aresch. differ from C. flexuosa Harv. and also from each other in the size of chromosomes, nuclei and also in the dimension of the swarmers, besides the dimension of the filaments and the types of branchings.
10. Microphotographs have been produced in support of the evidence of the presence of nucleoli and their dissolutions the presence of chromocentre like bodies and the choromosome counts from mitotic and meiotic divisions.
11. The method of staining by acetocarmine has been used for cytological study.