INTRODUCTION. 



39 



and first aim of Botanical knowledge ; tlie study 

 of" tlieir clusters becomes the aim of systematic 

 Botany : nomenclature and classification, which 

 may be compared to a kind of Statistical Sci- 

 ence, under a philosophical method, based on 

 accurate principles. 



Species are the collections of individuals per- 

 fectly alike in all their parts. Varuties are 

 slight casual deviations. Breeds or Proles are 

 permanent Varieties. Therefore Species are 

 natural altho' variable. 



Genera are the collective groups of Species, 

 that agree in the characters of the fructifica- 

 tion. No Species belongs to a Genus unless it 

 agrees with all the others therein included. 

 Sub-Genera are lesser groups or sections with 

 some slight deviations chiefly in the habit, sel- 

 dom in the floral organs. Therefore proper 

 Genera are also natural. 



Natural Families are groups of Genera 

 having some striking characters in common, 

 chiefly floral and organic. 



Natural Orders are groups of families 

 united by one or several important characters, 

 chiefly floral and organic. 



Natural Classes are groups of Orders, pos- 

 sessing some very peculiar floral characters, 

 and common organization. 



By attending to these successive groups, and 

 never forcing into them any stranger by organic 

 characters, we may hope to rectify them, im- 

 prove and fix invariably. 



If the natural Classes of Plants were as stri- 

 king as those of Animals, and known at first 

 sight like Birds, Snakes, Insects &lc. we should 

 not have had so many difiiculties in seeking 

 them. But even Reptiles, Insects &c. oflfer 



