306 PEKNS : EEITISH AND FOREIGN. 



as may be seen in some of the nurseries ani market- 

 gardens near London, it produces fronds 2-3 feet in 

 Jength. The Asplenium Trichomanes, A. Ruta-muraria, 

 Geterach officinarum, andPolypodiumvulgare, are also 

 "waU and tombstone-loverSj and may be called our 

 domestic Ferns. 



Another remarkable example of a Fern making 

 itself at home under extremes of temperature and 

 moisture, is Pteris longifolia, a species having a wide 

 range throughout the tropical and sub-tropical regions 

 of both hemispheres. On the island of Ischia (Bay 

 of Naples) it is found luxuriating within the influence 

 of the hot vapours rising out of the cavities left by 

 extinct volcanoes, growing in soft muddy soil at a 

 temperature ranging from 140° to 160°. In our 

 hothouses its spores vegetate abundantly upon all 

 moist surfaces, and in the crevices of brick walls. 

 Plants of it are nearly always to be found over the 

 openings of hot-water tanks, and it has been seen 

 in crevices of the walls outside hothouses, or even 

 under iron gratings, where it could receive but little 

 light, and where the temperature was often near the 

 freezing-point. In the dry air of the Cactus-house 

 plants of it have produced fronds from 2-3 feet in 

 length. 



In general the .fronds of Ferns remain long in a 

 perfect state; the exceptions to this rule are com- 

 paratively few, and these are chiefly supplied by the 

 natives of climates alternating with seasons of heat 

 and cold. But as many species are wanderers and 

 conform to th? effects of various climates, it is no 

 wonder to see some of our native Ferns assuming 

 the evergreen habit of their -foreign allies, when 



