Regeneration 239 



when the leaf was a lateral branch of indeterminate growth. In most fern 

 leaves, unlike those of angiosperms, growth continues longest at the tip 

 and in some species the leaves root readily there. It is thus to be expected 

 that fern leaves should sometimes reconstitute new tips if the old ones 

 are injured or removed. Goebel (1908) with Polypodium and Figdor 

 ( 1906) with Scolopendrium cut away a small bit of tissue from the grow- 

 ing leaf tip and found that this meristematic region was reconstituted 

 but that a double or forked lamina was produced. 



Fig. 9-2. Diagram of transverse section of apex of Primula in which a central plug of 

 pith was isolated by four vertical incisions ( broken lines ) . In this plug a new vascular 

 cylinder has been regenerated at a constant distance from the surface. (From Ward- 

 law.) 



Among higher plants, leaves of some of the Gesneriaceae are easily re- 

 generated. In Saintpaulia and some species of Streptocarpus, Figdor 

 ( 1907 ) split a young leaf nearly to the base along the midrib and found 

 that a considerable amount of new lamina was regenerated from the 

 basal part of the cut surface, which is the latest to mature. If the blade is 

 removed from a young primary leaf of Cyclamen, two new blades re- 

 generate by reconstitution of the meristematic region at the sides of the 

 petiole apex (Winkler, 1902). Figdor also reported (1926) that if the 



