236 EVOLUTION 



ogy of the germ-cells; while some of the best 

 chapters of Spencer's "Principles of Biology" 

 are those in which, after pointing out its 

 intelligibility in terms of the principle of con- 

 servation of energy, he elaborates the an- 

 tithesis of nutrition and reproduction by 

 reference to many plant and animal forms. 

 Yet though the principle is one familiar 

 since the dawn of physiology, its applica- 

 tions are still far from exhausted. "While 

 philosophers are disputing over the govern- 

 ment of the world, hunger and love are per- 

 forming the task," says Schiller; and our 

 "Evolution of Sex" is essentially an elabora- 

 tion of one great aspect of this theme. 



APPLICATIONS TOWARDS INTERPRETATION 

 OF THE PLANT WORLD. Let us begin with 

 the origin of the flower, which all agree in 

 regarding as a shoot modified for reproduc- 

 tion. But it is also shortened, as compared 

 with a vegetative shoot; then why? By 

 natural selection from two other alternative 

 variations? one like the vegetative shoot, 

 and the other lengthened farther still? These 

 are imaginable as forms; there is no mor- 

 phological absurdity about them: yet we 

 may be fairly sure they never existed at all, 

 and so have not been selected. How so? 

 They are excluded by the physiological 

 explanation of inevitable shortening; since 



