24 



FLORA IND1CA. 



all tliis proves nothing ; but when we add the tacit acquies- 

 cence of Robert Brown, and of all other botanists who have 

 lived amid a tropical vegetation, and devoted themselves to 

 its study, it will not be considered surprising that we should 

 suspect such evidence as has hitherto been adduced by local 

 observers only, and in very limited areas. 



The subject of hybridization is however well worthy of the 

 attention of the tropical botanist ; and both in his garden and 

 in the field, he should keep his attention always alive to the 

 importance of observing every phenomenon that may bear 

 upon its agency, and should institute operations that will 



light 



B. On Variation of Species. 



Although the researches of naturalists have not hitherto 

 led to the detection of those laws in obedience to which many 

 species of plants vary much in one climate and less in others, 

 or remain constant throughout many climatic conditions, they 

 indicate the operation of certain general laws, whose effects 

 are as follows : 



1 . Contiguous areas, with different climates, are peopled by 

 different species of plants, and not by the same under differ- 

 ent forms. 2. Similar climates in AiWnf flW * a o™> Tint neonled 



same 



natural orders of plants. 



and remote 



admixture of species common to two or all 

 ot them, which retain their individuality under every change 

 of climate. 



These are generally admitted facts ; there are however ex- 

 ceptions, upon which are based the arguments for attributing 

 to climatic effect, the creation of many species from one vain 

 able type. Careful observation reveals many 8Uch exceptions ; 



and the tendency winch pl auts display to revert to one tvnical 



specie*. 



The contrary inference, that atv*n«a -^ -~» « A t 



<kx» not f««tii to h* J ™ P T^ m 8Ub J° ot to a certain amount of 

 , ciom not Main to have oerunv.i to him. 



