176 CLASSIFICATION. 



Having considered the meaning of individual, species, genus 

 &Di<\fanu/y, and of the characteristics by which these are group- 

 ed together, let us take a general view of this subject.' 



It is evident by the formation of species, genera and families, 

 that every species should offer the essential characters of the 

 family and genus to which it belongs ; while the marks which 

 distinguish this species from another species of its genus, will 

 be such as do not belong to the whole genus or family. The 

 different genera in families are also distinguished by characters 

 which do not belong to the whole family; every individual, 

 then will possess its specific character, its generic character, 

 ,and its family character. 



The specific character is less important than the generic, as 

 it is mostly founded on the characters of the organs of vegeta- 

 tion, which we have seen are isolated and less important than 

 the coexistent characters. We often find in the analysis of 

 plants, a great difficulty in determining their species, from the 

 want of more definite marks of distinction. 



Generic characters are mostly of the coexistent kind, and 

 are more valuable than the specific characters. The distinc- 

 tions of genera are usually much more apparent than those of 

 species ; as a rose can be more easily distinguished Jrom a pink, 

 than one species of rose from another species. Families are 

 grouped together by marks of resemblance found in genera. 

 These family characters are of all the most important. 



In the artificial classes and orders we depend on what we 

 have before termed factitious characters. 



In species, genera and families, the essential characters are 

 also natural characters. 



LECTURE XXII. 



* Natural Families. 



We will now consider the vegetable kingdom as divided into 

 natural families. We first find the general division, Acotyle- 

 donous plants ; these are the lowest in the scale of vegetable 

 life, resembling, in many respects, the lower orders of animals ; 

 like them, simple and almost homogeneous in structure, and 

 chiefly composed of cellular texture. 



General view of the subject of classification Which is the more important, 

 the specific or generic character? Why are generic characters most valu- 

 able ? - How are families grouped together ? Artificial classes and orders 

 First general division of plants. 



