Cytology of Cutleria and Aglaozonia. A Preliminary Paper

Abstract

The nuclear conditions during the life-history of Cutleria multifida and Aglaozonia reptans may be summarized as follows: 1. The nucleus of both male and female plants of Cutleria multifida contains 24 chromosomes; and the male and female gametes produced contain the same number. 2. In the union of gametes the number is doubled, and 48 chromosomes appear in the sporelings, which develop into the Aglaozonia form of Cutleria. Therefore it is evident that the individual bearing the name of Cutleria multifida represents the gametophytic phase of the species, 24 being the gametophytic number of chromosomes; and the Aglaozonia form of Cutleria represents the sporophytic phase of the species, 48 being the sporophytic number. 3. Aglaozonia reptans contains 48 chromosomes, and the number is reduced in zoospore formation, the zoospore containing 24 chromosomes. The zoospore with the reduced number of chromosomes germinates without conjugation. Although the nuclear details of the sporelings of Aglaozonia reptans have not yet been followed, it seems evident that Aglaozonia reptans represents the sporophytic phase of the individual whose gametophytic and sporophytic numbers of chromosomes are respectively 24 and 48. Probably Aglaozonia reptans as it occurs in nature is identical with the Aglaozonia form of Cutleria multifida which we have grown under culture and is now determined to be the sporophytic phase of the species.