n. UNCERTAINTY OF SPECIES. 41 



put forth by technical botanists, whose business it should 

 be to know species, but who too often only describe 

 plants. 



Of late years it has been made compulsory on Students 

 of Medicine to acquire a smattering of botany, although 

 useless to them as medical practitioners. From this 

 hardship imposed on the students some benefit has 

 accrued to the purses of professional botanists. Among 

 other ways, it has caused a considerable demand for such 

 Floras and other elementary works as are adapted for 

 class-books in the lecture-room, and are portable in the 

 jGleld. Hence there have been new editions, in rapid 

 succession, of Hooker's British Flora and Babington's 

 Manual of British Botany ; and the latter work will 

 afford a suitable illustration, bearing on the uncertainty 

 of species in books. 



Four successive editions of the Manual, to appearance 

 each one carefully revised by the Author, have been pub- 

 lished in about a dozen years. The Author of the 

 Manual may be said to know the special botany of the 

 British Islands far more completely and critically, than it 

 is known either by the first Author or recent Editor (Dr. 

 Arnott, editions 6 and 7) of the British Flora. On this 

 account the four successive editions of the Manual, — 

 dated in 1843, 1847, 1851, 185G,— may afford a good cri- 

 terion and example of the uncertainty of species, by a 

 selection of several genera and generic sections which are 

 differently divided into species in the various editions. 

 (See the subjoined list, on the following page). 



In this list the genera are so placed as to bring into 

 view the fact, that the changes are not in one direction 

 only, but in the two opposite directions of increase and 

 decrease in the numbers of the species ; further, that 



VOL. IV. ,G 



