: theless it affords ample materials for verifying and | 
ON GENERA AND SPECIES. 
ciated with a host of species differing widely in habit 
Admitting that a greater or lesser number of species à 
possess some character in common to entitle them to be - 
called genera, nevertheless, genera may be said to have no 
real existence in nature, but, by adopting them, we are ` : 
enabled to study and classify Ferns so as to convey to the - 
mind our ideas regarding the various forms and nature of - 
the numerous plants that come under our observation. 
In the preceding observations I have shown that habit 
is of great importance as a character for determining the : 
relationship of Ferns to one another, either as individual ` 
species or groups of species, but habit is not always avail. ` 
able, especially in describing from herbarium specimens ` 
alone, for it is only the small growing kinds, with caudex ` 
and fronds united, that are suited for the herbarium. A 
great number consists of single fronds, or even portions of 
fronds, only, consequently, the nature of their vernation is 
. unknown. Indeed, the great botanists of the present day 
_ Content themselves with describing plants from dried spe- 
~ ¢imens, many of which are often small and imperfect, and 
_ fail to convey the true nature of the plant in its living 
_ The celebrated botanist Mr. Bentham says :—“I have 
. published several thousands of new species of plants, I 
: P never published one without examining it in a her- 
‘barium, and I have examined very few in botanical 
. |gardens." This practice I call unfortunate, for although 
` the living collection at Kew may not at any time exceed 
-~ one-tenth of the species in the herbarium collection, ne 
: to correct errors in many descriptions made from herbar A am 
. Specimens only. With regard to the collection of livin 
.. Ferns, which the author of the “ Species Filicum ” cal 
