6 INTRODUCTION. 



together the water will remain fresh, by each ab- 

 sorbing the exhalations of the other. 



The many divergencies or ramifications which, 

 after the primary, took place in each of these lines 

 of development, cannot now, and probably never 

 will be, accounted for. 



These divergencies and their ramifications may 

 be compared to the branches of a pedigree. They 

 represent, in fact, ancestral conditions, and are the 

 true history of nature. 



It is evident that divergencies cannot be arrang- 

 ed iu a straight line. Our ancestors have striven 

 without success to accomplish this feat, and have 

 given it up in despair. 



Modern science is content to investigate the dif- 

 ferent lines in which organic life exhibits itself, 

 and to study the characters common to the mem- 

 bers of a given line, as well as those by which they 

 differ, from other lines. This process is called 

 " Classification." 



By another process of reasoning, science endeav- 

 ors to find the point from which several lines di- 

 verged. This starting point is called "the connect- 

 ing link," and the process of arranging the differ- 

 ent lines of types around their respective starting 

 points, is called " Systematizing." In some rare 

 cases the "connecting link," or better, the starting 

 point, of two lines of evolution still exists, retaining 

 enough of its original characteristics to coincide 

 with the ideal of the connecting link, if it were 

 evolved by a process of reasoning. 



