Mitotic Index in Selected Red AlgaeIn SituI. Preliminary Survey

Abstract

A review of the literature indicated a lack of quantitative data on cell division in macroscopic algae in the laboratory and particularlyin situ.By means of SCUBA techniques selected red algae were collected from theirin situlocation on a 24 h basis through the seasons of the year. The varied oceanographic and meteoro-logical conditions on the southern tip of Vancouver Island provided shore habitats of adequate contrast.Rhodomela larixwas found to be a suitable test species for quantitative work, and differentials in mitotic activity in the growing parts of this plant were explored. Using squash techniques a method of quantitative estimation of mitotic activity employing a point-counting method was developed. It was found necessary to define the limits of mitotic phases inR. larixto facilitate quantitative analysis which was carried out over 24 h periods both in July and in February. Mitotic activity inR. larixshowed a well-marked periodicity, although only the July data are statistically significant. The distribution of mitotic activity throughout the day was similar both in July and in February despite the dissimilarity of photo-period, temperature and tidal factors, which suggests the presence of a circadian rhythm. This preliminary work is being continued by furtherin situinvestigations correlated with laboratory cultures under controlled environmental conditions.