THE EVOLUTION AND VARIATION OF FRUIT PLANTS. 19 



has been assigned the duty of building up structure and of 

 transforming the energy of lifeless matter into that of living. 

 From the shapeless mass of protoplasm as a microscopic speck 

 the varied processes of development are laid down in orderly 

 sequence. The living plant passes through definite changes 

 before it obtains the form and likeness of the parent, wluch varia- 

 tions mark its pathway'' from shapelessness to the characteristic 

 form of its race. And this germinal matter exhibits changes of 

 form and other movements which are not explained by any 

 physical property or extraneous influences ; the probatie cause of 

 the first formation of cells being, that various influences from 

 without, on a minute mass of vitalized but inorganic matter, 

 determine a slight hardening of the surface. The evolution and 

 the development of fruit plants are really synonymous terms ; their 

 growth is simply a process of enlargement by which were evolved 

 from a particle of matter called a germ, a substance potentially 

 alive, having within itself the tendency to assume a definite living 

 form. And this germ is not merely a body in which life is 

 dormant or potential, but is simply a detached portion of the 

 substance of a pre-existing living body. The process of evolution 

 consists in a succession of changes of the form and functions of 

 the germ, by which it passes from an extreme simplicity of visible 

 structure to a greater or less degree of complexity ; and this 

 course of progressive differentiation is usually accompanied by 

 growth effected by intussusception. This germ is only a nucle- 

 ated cell — the vesicle contemplated as the fundamental form of 

 organization — the meeting point between the inorganic and the 

 organic, the end of the mineral and the beginning of the vegetable 

 kingdom. The first step in the process of evolution is the divi- 

 sion of the cell into two or more portions, which process is 

 repeated until the organism from being unicellular becomes 

 multicellular ; the single becomes an aggregate cell, and to the 

 growth and transformation of the cells produced from this aggre- 

 gate do all the organs and tissues of the adult owe their origin. 



Fruit plants may be regarded then as the modified descendants 

 of pre-existing organisms, and not the unchanged posterity of 

 similar forms of life originally specially created. The discovery 

 of the indefinite remote ancestors of all plants, as represented by 

 the monera, structureless infinitely small jelly-like beings, repre- 

 sentatives of a kingdom intermediate between the animal and 



