6S 



without the intervention of the spore, has presented itself 

 in several forms, such as soral apospory, in conjunction 

 with the aborted sori or spore heaps, or apical apospory, 

 by simple extension and modification of the frond tissue 

 itself. It had so far, until Professor Goebel's investiga- 

 tions,''' been confined to otherwise abnormal varieties, and 

 on some of these apospory only presented itself or could be 

 induced to appear under special cultural conditions. Thus, 

 in the case of Athyriuni filix-fosmina vav. tmco-glomeratum, 

 Dr. F. W. Stansfield has shown that, despite the quite 

 deciduous nature of the species, the extremely comminuted 

 crests retain vitality through the winter under close culture, 

 and produce both bulbil and aposporous outgrowths in the 

 following spring. Professor Goebel's investigations lead, 

 however, far beyond this, since a considerable number of 

 quite normal species are found to produce aposporic and 

 apogamic prothalli, as also simple asexual plants, if the 

 primary or first fronds produced from the prothallus are 

 severed therefrom and layered on sterilised turf or loam. 

 Among the plants so treated he mentions particularly 

 Aneimia Dvegeana^ Alsophila van Geeviii, Cevatoptens thalic- 

 troides, Gymnogramma chvysophylla, Polypodiiim aureum, and 

 Ptevis longifolia^ of most ot which he gives illustrations 

 showing the diverse methods in which these regenerative 

 outgrowths appear on the layered primary fronds. Since, 

 however, these species were taken purely by chance from 

 a large collection, the presumption is justifiable that the 

 great majority of species possess the same regenerative 

 faculty, though it appears to be confined to the first fronds, 

 in which a hard-and-fast line between thegametophytic and 

 sporophytic generations does not yet appear to be drawn. 

 Hence, when the normal process of growth is interrupted 

 by severance from the prothallus, and favourable conditions 



* ExperimenteUe morphologische Mittcihingen, by Karl Goebel. Reporte 

 of the Royal Bavarian Akademie der Wissenschaften. Vol. xxxvii., 

 1907 ; Part II. 



