A Family History. 201 



descent from an earlier common ancestor. Each of 

 them has been produced by the selective action of 

 nature, which has favoured certain individuals in the 

 struggle for existence, at the expense of others, and 

 has thus finally resulted in the establishment of new 

 species, having peculiar points of advantage of their 

 own, now wholly distinct from the original species 

 whose descendants they are. Looked at in this 

 manner, every family of plants or animals becomes a 

 sort of puzzle for our ingenuity, as we can to some 

 extent reconstruct the family genealogy by noting 

 in what points the various members resemble one 

 another, and in what points they differ among them- 

 selves. To discover the relationship of the various 

 English members of the rose tribe to each other-^ 

 their varying degrees of cousinship or of remoter 

 community of descent— is the object which we set 

 before ourselves in the present paper. 



Perhaps the simplest and earliest type of the rose 

 family now remaining in England is to be found in 

 the little yellow potentillas which grow abundantly in 

 ill-kept fields or by scrubby roadsides. The poten- 

 tillas are less familiar to us than most others of the 

 rose family, and therefore I am sorry that I am 

 obliged to begin by introducing them first to my 

 reader's notice rather than some other and older 



