111 KKDITY AND KVoUTION IN PLANTS 



into foliage-leaves. Similar results were also obtained by 

 Goebel. These experiments indicate that foliage-leaves 

 and sporophylls are very closely related to each other, 



f 



FIG. 16. Portion of a leaf of a fern (Tcctoria cicutaria) that 

 bulbils on both the upper and lower surfaces of its leaves. Plantlcts 

 develop from the bulbils while they are still attached. 



and demonstrate clearly that foliage-leaves may be pro- 

 duced by the sterilization of spore-bearing leaves. The 

 interesting question here naturally arises as to whether, in 

 the evolutionary development of the plant kingdom 



