10 BIONOMIC LAWS. 



whether the evolution of species is anything more than a doubtful 

 hypothesis. In other words, it may be thought that the attempt to 

 explain the method of evolution before it has been proved that there 

 is such a process is an inversion of logical method. Further consid- 

 eration will, however, show that the greatest obstacle to the general 

 acceptance of the theory of evolution has been the difficulty in believ- 

 ing that this wonderful transformation is being wrought out in our 

 very presence, and that the laws in accordance with which it pro- 

 gresses are in a large degree open to investigation. 



The possibility of recognizing this stupendous reality has been shut 

 out of the mind by the double assumption that the methods of crea- 

 tion are necessarily inscrutable and that the process of creation has 

 been closed never to be reopened. As both these assumptions are 

 without proof, the shortest method of setting them aside is to show 

 that the energies of creation are ever working in the ordinary pro- 

 cesses of life. The effectiveness of this general method of appeal to 

 actual experience and observation is seen in Darwin's "Origin of 

 Species." He there first shows that a process of breeding, which in 

 domestication always results in divergent varieties, is also being car- 

 ried on by natural causes. He then shows that if we assume that 

 species have been produced, one from another, by some such process, 

 the relations of species to species, not only in the groups of scientific 

 classification, but also in their geographical distribution over the 

 earth and in their geological successions in time ; become intelligible, 

 and present a network of interrelated and significant phenomena, the 

 causes of which can be more or less fully traced. I propose to follow 

 the same general method. But as present debate relates to the prin- 

 ciples and causes on which evolution depends rather than to the proof 

 that such evolution has taken place, I shall give my chief attention 

 to the first part of the argument. I shall discuss the forms and laws 

 of bionomic action by which the relations of species to species are 

 being maintained or modified, and shall refer to the results of this 

 action as revealing the nature of the process. 



3. Need of Investigation of all the Forms of Interaction causing 

 Transformation. 



Inquiries leading to the discovery of bionomic laws have usually 

 been first suggested by observing the relations under which organ- 

 isms present themselves as distributed in nature; but after we have 

 once recognized the fact that these relations are the result of the 

 constant interaction between organism and organism, and between 

 the organism and the physical environment, it becomes necessary to 



