THE EVOLUTION AND VARIATION OF FRUIT PLANTS. 17 



plant was balanced by generation, its extinction has been concom- 

 itant with the Creative power which has continued to provide a 

 succession of species. But palseontology does not teach the law 

 according to which species of fruits have been introduced. Their 

 mysterious introduction is veiled from us and can never be pene- 

 trated, except it can be traced in the gradual departure of varieties 

 from the type of the species. The principle adopted by Nature, 

 which seems to produce permanent useful varieties, and then spe- 

 cies afterwards, under wider divergencies perhaps, is the principle 

 of selection. Nature is so orderl}' and systematic that every race is 

 continued by those individuals that are best adapted to the 

 circumstances of the day ; and in this way is preserved in harmony 

 the grand scheme of creation, according to which life is every- 

 where present, and is always tending to higher forms of develop- 

 ment when circumstances are favorable. 



The investigation of the development of a fruit plant leads us 

 directly then to the germ from which it springs. Commencing 

 with a simple cell, it is impossible to tell what form it is destined to 

 take, its vitality cropping up like some unseen but felt presence 

 that hovers around the biological secret. The life history of 

 a fruit plant shows a complex collection of manufactories 

 and organizations ; but the structure of the germ acquired by 

 natural selection seems to be completely sufficient for producing 

 mechanically a numerous variety in the struggle for existence. 

 Some naturalists affirm that when individual species of fruit 

 plants were brought into existence, individuals of genera widely 

 diffused themselves, by the difference of localities, nourishment, 

 and soil, formed varieties, and in consequence of their isolation 

 having never been crossed and brought back to the main type, in 

 the end became permanent and distinct species. A few declare 

 the different species to be the specified productions of the forma- 

 tive tendencies of plants that arise from the various combinations 

 of the fundamental forces of organic matter ; others who have 

 adopted the theory of development have only arrived at the 

 conception that ever}' species of a fruit plant is the gradually 

 changed and transformed descendant of one or a few original 

 prototypes. 



It was difficult to unravel the mystery of the life of a fruit plant 

 when there were no clear ideas regarding the constitution of 

 bodies or the composition of chemical aggregates ; but all species 

 2 



