210 



PElNCIPLES OF PLANT-TEEATOLOGY. 



ostrich-fern (Struthiopteris germanica), in which the 

 differentiation into fertile and sterile fronds also occurs, 

 Goebel, by cutting off the sterile fronds, induced the 

 sporophylls to exhibit their conformation, but bearing 

 vestigial sporangia. 



In the royal fern {Osmunda regalis) and 0. cinna- 

 momea the fertile pinnae may often become partially 

 foliaceous; in the first-named plant the pinnules of 

 such pinnae may have one longitudinal half fertile and 



138. ICr. 



Pia. 138. — Botrychium Lunaria (Moonwort). Sterile portion of sporo- 

 pliyll bearing fertile segments. (After Goebel.) sp, sporangia ; 

 /, base of fertile " spike." 



Fia. 139. —Aneimia Dregeana. Basal portion of sporopbyll showing 

 sterile lowest pair of pinnae. 



the other sterile, or the upper half may be sterile, while 

 the lower is fertile and contracted to the midrib. 



In the moonwort {Botrychium Lvnaria) the whole 

 of the ventral fertile segment or sporangiophore may 

 become entirely sterile and foliaceous ; more fre- 

 quently only certain pinnae or portions of such undergo 

 this change. 



In Aneimia Dregeana the two lowermost fertile 

 bipinnate segments were seen in a perfectly sterile 

 condition in a dried specimen which had been collected 

 by Mr. T. R. Sim near King William's Town, Cape 

 Colony. The sterile segments were not quite so much 



