302 CONCLUSION, LChap. XV. 



speak from experience — does the study of natural history 

 become! 



A grand and almost untrodden field of inquiry will 

 be opened, on the causes and laws of variation, on cor- 

 relation, on the effects of use and disuse, on the direct 

 action of external conditions, and so forth. The study 

 of domestic productions will rise immensely in value. 

 A new variety raised by man will be a more important 

 and interesting subject for study than one more species 

 added to the infinitude of already recorded species. 

 Our classifications will come to be, as far as they can 

 be so made, genealogies; and will then truly give what 

 may be called the plan of creation. The rules for classi- 

 fying will no doubt become simpler when we have a defi- 

 nite object in view. We possess no pedigrees or armorial 

 bearings; and we have to discover and trace the many 

 diverging lines of descent in our natural genealogies, by 

 characters of any kind which have long been inherited. 

 Rudimentary organs will speak infallibly with respect 

 to the nature of long-lost structures. Species and groups 

 of species which are called aberrant, and which may 

 fancifully be called living fossils, will aid us in form- 

 ing a picture of the ancient forms of life. Embryology 

 will often reveal to us the structure, in some degree ob- 

 scured, of the prototypes of each great class. 



When we can feel assured that all the individuals 

 of the same species, and all the closely allied species 

 of most genera, have within a not very remote period 

 descended from one parent, and have migrated from 

 some one birth-place; and when we better know the 

 many means of migration, then, by the light which 

 geology now throws, and will continue to throw, on 

 former changes of climate and of the level of the land, 



