LAW OF PROGRESSIVE COLOURATION. 39 



fertilization or in special adaptation for dispersal of 

 seeds results in a lessening of the number of carpels 

 or of seeds. The plant does not need to produce so 

 many when all are fairly sure of arriving at maturity 

 and being dispersed. 



Flowers in which the carpels have arranged them- 

 selves in a circle around a common axis, like the 

 Geraniacece and Malvacece, thereby show themselves 

 to be more highly modified than flowers in which all 

 the carpels are quite separate and scattered, like the 

 simpler Rosacecs and Rammculacece. Still more do 

 families such as the Caryophyllacecs^ or pinks, in which 

 all the five primitive carpels have completely coalesced 

 into a single five-celled ovary. Accordingly, it is not 

 remarkable that the pinks should never be yellow. 

 On the other hand, this family has no very specialised 

 members, like the larkspur and the monkshood, and 

 therefore it very rarely produces bluish or purplish 

 flowers. Pinks, in fact, do not display so wide a 

 range in either direction as Ranunculace<s. They 

 begin as high up as white, and hardly get any higher 

 than red or carnation. They are divisible into two 

 sub-families, Alsinece and Silenece. The Alsinecs have 

 the sepals free, the blossoms widely expanded, and no 

 special adaptations for insect fertilization (Fig. 14). 

 They include all the small undeveloped field species, 

 such as the chickweeds [Stellaria media, Arenaria trin- 

 erviSf Cerastiiim vu/gattun, &c.), stitchworts {Stellaria 

 holostea, &c.), and cornspurries {Spergula arvensis), 

 which have open flowers of a very primitive character ; 

 and almost all of them are white. These are ferti- 

 lized by miscellaneous small flies. The Silenece, on the 

 other hand, including the large- flowered types such as 



