igig] STEIL—PTERIS 47 1 



of 4 forms of Polystichum angulare, one of Laslrea, and 3 of Athyrium 

 Filix-foemina, Stansfield in a similar manner induced apospory. 

 He is inclined to believe that apospory may be induced by the same 

 method in many other species of ferns. 



GoEBEL (14) discovered apospory in Asplenium dimorphum. 

 The ends of a finely divided leaf of a plant of this species produced 

 prothallia, tx-pically heart-shaped, and bearing both archegonia 

 and antheridia. The nuclear history was not investigated, but 

 GoEBEL suggests that reduction theoretically occurs when the 

 prothallia are formed. Goebel (15) successfully induced apospory 

 in Aneitnia Dregeana, Alsophila van Geertii, Ceratopteris thalictroides, 

 Gymnogramme chrysopJiylla, Polypodium aiireum, and Pteris longi- 

 folia. In Marsilia Drummondii and two Adiantum species the 

 results were negative. The primary leaves of young sporophytes 

 were removed and placed on sterihzed loam and peat. From the 

 lamina and petiole of the leaf, thus treated, there were produced 

 gametophytes, sporophytes, or forms intermediate in character, 

 since such outgrowths in some cases bore both antheridia and 

 stomata. The aposporously produced prothalha of Pteris longi- 

 Jolia developed antheridia and archegonia. Sporophytes were not, 

 however, observed to develop from the prothallia. Since there was 

 found no great difference between the nuclei of the two generations, 

 Goebel concludes that there is no sharp line of demarcation 

 between gametophyte and sporophyte. As a result of a series of 

 experiments, Goebel found that young sporophyte tissue possesses 

 greater power of regeneration than old tissue. Contrary to 

 Bower's view that apospory is induced with difficulty and is rare, 

 Goebel is convinced that the phenomenon can be produced readily 

 and is widely distributed in ferns. Considered from the phylo- 

 genetic point of view, Goebel regards the prothallium of the fern 

 as a rudimentary leaf, bearing sexual organs. 



In a preliminary note on the cytology of apospory, Miss Digby 

 (5) described her results in inducing apospory in Lastrea pseudo-mas 

 var. cristata, the aposporal nature of which first had been reported 

 by Druery (9). As a result of the study of the nuclear condition 

 of the fern, it was reported that 50 chromosomes were retained 

 throughout the life cycle. 



