INTRODUCTION. 



Although we hold that the general proof of organic evolution is abundantly 

 self-evident, it is unfortunately all too true that its method is still an open 

 question. The discovery of the method of evolution and the question of 

 the origin of species is not, if we may judge by the prevailing diversity 

 of opinion among biologists, much nearer a solution than it was when Dar- 

 win left it. This does not mean that no advances have been made ; it simply 

 indicates that the question is deeper, broader, and more difficult to solve than 

 was at first supposed. 



The current hypotheses of the method of evolution, each supported by 

 evidence more or less convincing, and each capable of satisfactorily explaining 

 some phenomena, fail utterly to account for all the phenomena in the origin 

 of species. In other words, current hypotheses seem to be partial truths 

 only, and we are probably far from discovering the final truth concerning 

 the method of evolution. Since the publication of the ' ' Origin of Species, ' ' 

 the amount of literature concerning the general facts and method of evolution 

 has been stupendous. When we examine this literature, however, we find, 

 unfortunately, that it is far too much the writings of advocates of one or the 

 other of the current hypotheses and all too little that of the investigator. 

 On the question of the method of evolution biologists have grouped them- 

 selves into different schools, each strongly maintaining that his method is 

 the real one. With the facts put forward by Darwin and his contemporaries 

 and such new ones as have since been accumulated, these advocates have 

 built up ingenious pleas in favor of their hypotheses, but have had little 

 time left in which to attempt to penetrate farther into the unknown and get 

 new facts and more conclusive evidence. 



Biologists have gradually come to see, however, that any further advance 

 rests, not upon controversial and argumentative writings, but upon new 

 investigations so planned and executed as to bring to light new facts and 

 evidence, whatever they may be, and regardless of how they may affect cur- 

 rent hypotheses. Already we are beginning to have the fruit of this new 

 line of work, such as the well planned, clearly executed research of De Vries, 

 in which is presented a large body of new facts and evidence concerning the 

 origin of species in plants. Investigations of this character are, however, 

 the work of years, and a long time must necessarily elapse before any great 

 body of new data and evidence from these studies can be accumulated. 



Eleven years ago I began the study of evolution in the chrysomelid beetles, 

 especially in certain genera which are confined entirely to America, with the 

 idea that one ought by stud}', sufficiently long continued and properly con- 



IX 



