APOSPORY IN PTERIS SULCATA L. 



W. N. Steil 

 (with plates XVI, XVII, AND FOUR FIGURES) 



Historical 



Although apospory was discovered in the mosses by Pringsheim 

 (i8) and Stahl (19) a short time after apogamy had been found in 

 Pteris cretica albo-lineata by Farlow (ii), apospory remained 

 unknown in the Pteridophytes until Druery (6, 7) reported the 

 phenomenon in Athyrium Filix-Joemina var. darissima Jones, 

 Prothalha of this fern were observed to form either from the head 

 or the stalk of the sporangium which was arrested in its develop- 

 ment. The prothallia of aposporous origin produced antheridia 

 and archegonia. Druery (8) also reported the first case of apical 

 apospory, namely in Polystichum angulare var. pulcherrimum Wills. 

 The tips of the leaves of this species of fern produced the game- 

 tophyte as a direct vegetative outgrowth. 



Bower (2) published a brief summary of his investigations of 

 apospory in Athyrium Filix-foemina var. darissima Jones and 

 Polystichum angulare var. puldierrimum Wills, the material for the 

 investigation having been placed at his disposal by Druery. Sex 

 organs were also observed to develop on the prothallia of the 

 Polystichum angulare variety. The main portion of tl^e paper, 

 however, is not concerned with original studies, but with a discussion 

 of "short cuts" in the life history of the fern. 



Apospory was also discovered by Bower (3) in Trichomanes 

 pyxidiferum and T. alatum. In the former the gametophyte 

 generation was produced from aborted sporangia ; in the latter 

 there was soral and apical apospory. Sex organs were formed in 

 T. pyxidiferum, but in T. alatum archegonia were absent and 

 antheridia were never developed to maturity. Only, in T. alatum 

 were sporophytes observed to develop from the aposporously 

 produced prothallia, and these sporophytes were of apogamous 

 origin. Bower did not seem to be convinced that apospory and 



469 



