IV PREFACE. 



study has convinced the Author that they are required. 

 He may have fallen into error, but has earnestly endea- 

 voured to discover the truth. 



Attempts have been made greatly to reduce the number 

 of recognized species found in Britain ; but the results ob- 

 tained seem to be/So totally opposed to the teaching of the 

 plants themselves, and the evidence adduced in their 

 favour is so seldom more than a statement of opinion, that 

 they cannot safely be adopted ; nor does the plan of the 

 present wort admit of a discussion of the many questions 

 raised by them. Also it has been laid down as a rule by 

 some botanists, that no plant can be a species whose dis- 

 tinctive characters are not as manifest in an herbarium 

 as when it is aUve. We are told that our business as 

 descriptive botanists is not " to determine what is a 

 species," but simply to describe plants so that they may 

 be easily recognized from the dry specimen. The Author 

 cannot agree to this rule. Although he, in common 

 with other naturalists, is unable to define what is a species, 

 he believes that species exist, and that they may often be 

 easily distinguished amongst living plants, although some- 

 times separated with difficulty when dried specimens alone 

 are examined. He thinks that it is our duty as botanists 

 to study the living plants whenever it is possible to do .so, 

 and to describe from them ; to write for the use and in- 

 struction of field- rather than cabinet-naturalists ; for the 

 advancement of a knowledge of the plants rather than for 

 the convenience of possessors of herbaria ; also that the 

 differences which we are able to describe as distinguishing 

 plants being taken from their more minute organs, does not 

 invalidate their claim to distinction. It seems to be our 

 business to decide upon the probable distinctness of plants 

 before we attempt to define them — to make the species 

 afford the character, not the character define the species. 



