A Study of Preissia quadrata

Abstract

1. Twelve to sixteen archegonia are borne in each female receptacle, usually three to four in each quadrant, although as many as six were counted in a single quadrant of a receptacle. 2. Although fertilization is probably 100 per cent, the number of mature sporophytes in a single receptacle varies from one to six, the average number for over 100 heads was 2.98, the dominant number being four sporophytes to each head. 3. The sporogenous cells which metamorphose into elaters seem to be sister cells to the spore mother cells; therefore the number of spores is four times the number of elaters. 4. The number of spores to each capsule was estimated at about 3000; the average number for each head, therefore, would be nearly 9000. 5. The spores, although much less numerous than in Marchantia, are decidedly larger. Their diameter is about 75 μ, while the diameter of the spore of Marchantia polymorpha is not over 18 μ. The elaters of Preissia are smaller than those of Marchantia, although their number is greater in...