3 io 



CHAPTERS ON EVOLUTION. 



of another variety or species, the characters of the two different races 

 are combined and united in the " hybrid " progeny. Our gardens 

 and conservatories and, as we shall strive to show hereafter, the 

 natural plant-creation at large have benefited immensely in beauty' 

 from a knowledge of the changes in colour, form, and size, which 

 this " cross-fertilisation " may produce. For instance, the finest of 

 our rhododendrons are crosses in which the characters of Indian 

 and American species have been thus blended. The union of the 

 common heartsease with a large-flowered foreign pansy, has pro- 

 duced a new stock in which the excellences of both species are found. 

 The pelargoniums of our conservatories represent hybrid stocks 

 and varieties, which cross- fertilisation and cultivation have together 

 produced from the small-petaled species of South Africa. Such 

 results, among countless others, would seem to suggest that beneath 

 the subject of cross-fertilisation, or even underlying that of ordinary 

 fertilisation, there lies hid a mine of knowledge respecting the causes 

 which have wrought out the existing variety of plant- life. For the 

 plain and unfettered understanding of the subject in its less technical 

 phases, or to lay the foundations of knowledge respecting an interesting 

 field of natural-history study, no better subject could be selected than 

 the history of even the commonest flower such as a primrose. Rightly 



comprehending what is included in 

 the phases of primrose-life, we may 

 hope successfully to read some of 

 the more abstruse problems pre- 

 sented by the wider aspects of 

 plant existence at large. "The 

 ruthe primrose that forsaken dies," 

 and the "cowslips wan that hang 

 the pensive head," afford us delight 

 even when we are living in all the 

 simplicity of botanical ignorance. 

 It is not too much to say that their 

 systematic study may lead to the 

 higher delights and more cultured joys included in the knowledge of 

 some phases of natural law and in an understanding of the hows and 

 whys of living nature. 



The elementary botany of a primrose is a matter of few words. 

 Like every other perfect flower, it consists of four parts or circles of 

 organs placed one within the other. Outside, we perceive the circle of 

 fine green leaves, which we name the calyx, each green leaf of this organ 

 being named a sepal. In the primrose or campanula (Fig. 214), the 

 sepals are united, although in many other flowers, (e.g., buttercup and 

 wall-flower) (Fig. 205, ca\ we should find them free and separate. The 

 calyx of all flowers is, for the most part, coloured green, its obvious use 



A B 



FIG. 208. PRIMROSES. 



