ASPLENIUM PINNATIFIDUM. PINNATIFID SPLEEN-WORT. 1 95 



these tendencies develop that the fronds increase in productive- 

 ness. Dr. Chapman, in liis Flora, notes that he had seen a form 

 in which the two lower lobes had made prolongations horizon- 

 tally, in this resembling one of the characters of the Walking Fern. 

 The change of forni with approaching productiveness is a very 

 common characteristic in plants. Sometimes with entire leaves in 

 the infertile condition, they become divided in the ferdle, and some- 

 times the reverse is the case ; but the direction of change is always 

 uniform in allied species. It may be surmised from these con- 

 siderations that Asple7ihun pinnatifidiwt and Caniptosorus rhizo- 

 phyllus on modern theories of development were originally of 

 one parentage, and that the latter with more fertile tendencies 

 assumed those characters which seem inseparable from the more 

 fertile state. This speculation derives more force from the oc- 

 casional attempts of each to assume characters usually peculiar 

 in the other. The increased tendency to productiveness as the 

 fronds in the Walking Fern become deeper lobed, has already 

 been noted, as well as the tendency to barrenness in our present 

 species when its fronds are entire. In addition to this it some- 

 times happens that Asplcniiim pinnatifidum comes near "walking" 

 by the formation of a prolongation and the appearance of a small 

 swelling at the end. It is generally doubted that it actually roots 

 at the tip ; but Mr. Eaton observes that he has seen an enlarge- 

 ment at the apex, as if there were an attempt to form a prolifer- 

 ous bud ; and the writer of this once saw a similar case in a plant 

 growing in a green-house, where the prolongation reached over 

 to the ground with the enlargement apparendy ready to root, 

 when the frond was accidentally destroyed. Dr. Gray in our de- 

 scription quotes from some source, " the apex sometimes rooting;" 

 and Mr. John Smith in " HistoriaFilicum" places it in his division 

 of species actually rooting, and speaks of having had the living 

 plant to observe from. Our plant has straight veins, as seen in 

 our enlarged Fig. 2, while the Walking Fern has netted veins ; 

 but even these characters in ferns are known to be in intimate 

 relations with fertility. There is therefore no reason that we can 



