3°° 



Canadian Record of Science. 



originated as a sport under such conditions of superior care 

 and abundant nourishment as are generally found necessary to 

 the best growth of the plant. The chances that such a 

 change might have arisen under natural conditions in the 

 wild state, are possible but remote, and the present case is 

 therefore to be taken as an exaggerated expression — -an abrupt 

 and strongly marked development — of those alterations which 

 undoubtedly occur in the wild state, but often so gradually or 

 at such remote intervals, as to come under observation only 

 under the most favorable conditions of time and space. It is 

 nevertheless exactly in harmony with recognized alterations 

 under changed environment, such as Goessmann has long 

 since recorded when the wild grape is brought under cultiva- 

 tion, or such as Bailey has frequently directed attention to as 

 arising under cultivation, and such as are well known in 

 botanic gardens. 



The special feature of the Pierson fern is manifested in 

 the doubling of the frond, whereby the whole organ acquires a 

 most graceful, plume-like character. Normally the frond of 

 the specific form is once pinnate and upwards of 1.3 m. long ; 

 but it is a characteristic of the plant that the fronds are capable 

 of indefinite extension from their tips, a feature which is also 

 manifested in Pierson's variety. The pinnae of the species 



Fig. 8. Nephrolepis exaltata 

 piersoni. Normal pinna showing 

 auricle on the upper side, x \ 



Fig 9. Nephrolepis exaltata 

 piersoni. Pinnate pinna showing 

 the pinnules to duplicate the 

 pinnae, x \ 



are lanceolate, upwards of 8 cm. long and auricled on the 

 upper side. (Fig. 8.) This auricle, as will appear shortly, is a 

 potential pinnule which it may become under favorable con- 

 ditions. But here again, the indeterminate character which 

 belongs to the unmodified frond as a whole, and not to the 

 separate pinnae, is extended, in the variety, to each one of the 



