III.—The Gametophyte of Psilotum

Abstract

Considerable interest attaches to the unravelling of the complete life-history of the Psilotaceæ, since they are apparently the nearest living representatives of the Sphenophyllales.The recent description of the gametophyte of Tmesipteris by Prof. Lawson, whose figures 1 had the privilege of seeing before they went to press, and the discovery of the gametophyte of Psilotum, which is the subject of the present paper, form a first contribution to the solution of this problem. It is of some interest to note that there remains now no Pteridophyte the gametophyte of which has not been described.In the early part of this research I was fortunate in finding a locality near at hand in which Psilotum flourished, and therefore I had at my disposal abundance of spores and later numerous prothalli.