LA W OF PROGRESSIVE COLOURA TION, 29 



respect, agrimony more nearly represents the primitive 

 form, though its tall habit and large spikes of flowers 

 show that it also has undergone a good deal of modi- 

 fication. Nevertheless, the yellow members of the 

 potentilla group, in their low creeping habit, their 

 want of woodiness, and their simple fruit, certainly 

 remain very nearly at the primitive ancestral stage, 

 and may be regarded as very early types of flowers 

 indeed. It is only among handsome and showy 

 exotic forms, which have undergone a good deal more 

 modification, that we get brilliant red-flowered species 

 like the East Indian P. nepalensis and P. atropurpurea. 

 But as soon as the plants rise a little in the scale, 

 and the flowers grow larger, we get a general tendency 

 towards white and pink blossoms. Thus the Prunece 

 have diverged from the central stock of the rose 

 family in one direction, and the Pomece and Rosece in 

 another ; but both alike begin at once to assume white 

 petals ; and as they lay themselves out more and more 

 distinctly for insect aid, the white passes gradually 

 into pink and rose-colour. To trace the gradations 

 throughout, we see that the Rubece, or brambles, are 

 for the most part woody shrubs instead of being mere 

 green herbs, and they have almost all whitish blossoms 

 instead of yellow ones ; but their carpels still remain 

 quite distinct, and they seldom rise to the third stage 

 of pinkiness ; when they do it is generally just as 

 they are fading, and we may lay it down as a 

 common principle that the fading colours of less 

 developed petals often answer to the normal colours 

 of more developed. In the Prunece, again, the de- 

 velopment has gone much further, for here most of 

 the species are trees or hard shrubs, and the number 



