48 



BOTANICAL GAZETTE 



[JANUARY 



is able to express itself simultaneously in the 



mor 



maintainin 



•rmal 



New 



the basal segment on the upper side of the pinna, in correspond- 

 ence with the large tooth or auricle which stands there in normal 

 pinnae. The homoeotic character of the variation is unmistakable, 



though partial. 



In a specimen from the Torrey herbarium, at the 

 Botanical Garden, the frondescent pinnae of the lower section of the 



aberrant frond 



imitate an occa- 

 sional trick of the 

 species, by which 

 soriferousness may 

 run down the 

 margin of the sterile 

 y specimen, the lower 



Fig. 12. — Normal 



region, on the tips of the pinnae. In the Torrey 



frondlets (pinnae) are soriferous and constricted in their apical 



region, and the soriferousness runs down their margins on the tips of 

 the pinnules. 



Dicksonia punctilobula in the herbarium of Mr. F. G. Floyd 

 shows entropic homoeosis of an interesting type, inasmuch as the 



Fig. 13.— Homoeotic pinna in Osmunda cinnamomea (in herb. Floyd). 



primary segments become frondescent in imitation, not of the 

 but of the infantile, or nepionic, leaves. 



Asplenium thelypt 



Milton, Ma 



sixth pinnae frondescent (others in a less degree), the modification 

 proceeding upon the basis of the lobing already normally present in 

































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