in.] A BUTTERCUP. 21 



to the plant of their proper performance must be plain. 

 On this ground, therefore, and from the general constancy 

 which the parts of flowers present in their principal fea- 

 tures, both in the structure of the several parts and in 

 their relations to each other, in groups of plants which 

 from numerous general resemblances" we may reasonably 

 imagine to be related by descent (that is, related to each 

 other in the same way that Europeans are more nearly 

 related to each other than they are to the negro or Indian 

 races, or as the different kinds of fish are more nearly re- 

 lated to each other than they are to birds or reptiles), 

 botanists make use of characters afforded by the organs 

 of the flower and fruit, to mark, in words, the principal 

 divisions of the vegetable kingdom. Hence it is desirable, 

 before we proceed to consider the organs which are more 

 subject to variation, that we should acquire a correct no- 

 tion of the nature of the principal modifications to which 

 the parts of the flower are liable in different plants. 



With a view to this, and that you may be enabled at 

 once to commence the examination and the describing of 

 flowers, we shall proceed in our next chapter to compare 

 with that of buttercup the flowers of a few common plants, 

 representing the most important types, or kinds of modi- 

 fication, of floral structure. 



