INTRODUCTORY ESSAY. 19 



plantSj — a study which requires also a practical acquaintance 

 with organic chemistry, consummate skUl in handling the dis- 

 secting knife, and command over the microscope, a good eye, 

 a steady hand, untiring perseverance, and above all, a discri- 

 minating judgment to check both eye, hand, and instrument. 

 A combination of these rare qualities makes the accomplished 

 vegetable physiologist, and their indispensability gives physio- 

 logy its pre-eminence in practice. 



III. Subjects of Variation, Origin of Species, Specific Centres, 

 Hybridization, and Geographical Distribution. 



It has been with no desire of obtruding our views upon our 

 readers that we have ventured to discuss these obscure sub- 

 jects with relation to Indian plants, but from a conviction, 

 that in the present unsatisfactory state of systematic botany 

 it is the duty of each systematist to explain the principles 

 upon which he proceeds ; and we do it not so much with the 

 intention of arguing the subject, as of pointing out to students 

 the many fundamental questions it involves, and the means 

 of elucidating them. 



To every one who looks at all beneath the surface of de- 

 scriptive botany, it cannot but be evident that the word 

 species must have a totally dijQferent signification in the opinion 

 of different naturalists ; but what that signification is, seldom 

 appears except inferentially. After having devoted much la^. 

 hour in attempting to unravel the so-called species of some 

 descriptive botanist, we have sometimes been told that the 

 author considers all species as arbitrary creations, that he 

 has limited the forms he has called species by arbitrary cha- 

 racters, and that he considers it of no moment how many or 

 how few he makes. So long as this opinion is founded on con- 

 viction, we can urge no reasonable objection against its adop- 

 tion ; but it is absolutely necessary that the principle should 

 be avowed, and that those who think the contrary should not 

 have to waste time in seeking for nature's laws in the works 



