2 ON GENERA AND SPECIES. 



They vary considerably in size, many not being larger 

 than mosses and liverworts and of as delicate a texture ; a 

 very few partake of the character of shrubs, and about one 

 hundred and fifty assume the aspect of trees, some attain- 

 ing the height of fifty or more feet. 



As the special character of their structure is fully ex- 

 plained further on, the above is sufficient to give an idea of 

 the nature of Ferns. 



Although Ferns possess but few economic properties, 

 either as food, medicine, or in the arts, they have never- 

 theless become of great interest to botanists, their study 

 being termed Pteridology, on which many books have been 

 written, and during the last fifty years have also come into 

 special favour with amateur plant cultivators, and lovers of 

 pretty plants. The constant desire for novelty has led 

 both public and private plant collectors and persons living 

 in foreign countries to devote special attention to the col- 

 lecting of Ferns, both for herbarium specimens and also as 

 living plants. By these means the collections of Europe 

 have become greatly enriched. It is recorded that the 

 Koyal Herbarium at Kew contains 50,000 specimens of 

 Ferns, which have been communicated by no less than 

 about 150 public, private, and trade collectors from all 

 regions : the Fern collection in the herbarium of the 

 British Museum is also very extensive. These, with the 

 living collection at Kew, which in 1864 contained above 

 one thousand species, have afforded ample means for study 

 and determining the genera and species of Ferns. Many 

 extensive living collections are also formed by amateurs, 

 who in rivalry enhance their value to such an extent that 

 as much as fifty guineas is frequently given for a single 

 plant of fashionable repute- at the time. 



Of late years many books have been published on Ferns, 



