CHROMOSOME NUMBERS IN THE PHAEOPHYCEAE

Abstract

The chromosome numbers for 95 of the approximately 1500 spp. of Phaeophyceae are summarized from published literature and some unpublished data. All orders within this algal class are represented except the Desmarestiales. Varieties of cytological techniques used by the investigators in dealing with the exceptionally small chromosomes of the brown algae, counting the chromosomes at slightly different times in the division cycle, and difficulties in distinguishing the chro-matids have undoubtedly led to discrepancies and inaccuracies in the reported numbers. Therefore, it is impossible to make any definite comparative statements or draw any conclusions from the data at the present time. Tentative basic numbers may be assigned to the orders as follows: Ectocarpales, 8-12; Dityosiphonales, 8-13; Scytosiphonales, 11-12; Cutleriales, 11-12; Sporochnales, 10; Laminari-ales, 8-13; Tilopteridales, 10-12; Sphacelariales, 8-12; Dictyotales, 8-12; Fucales, 8-12.