CHAP. XV.] THE TEDIGBEE AND OEIGIN OF THE GAT. 519 



every species of two occipital condyles ratlier indicate a Batrachian 

 ancestry. On tlic whole it seems probable that the Mammalia, and 

 therefore the Cat, descended from some highly-developed, somewhat 

 Keptile-like, Batrachian, of which no trace has yet been found. The 

 yet more remote ancestor of such Batrachian will have to be sought 

 amongst extinct and unknown fishes, intermediate between Ganoids 

 and Elasmobranchs, but with considerable fundamental affinity to the 

 Hays, however different from them they may have been in external 

 aspect. Beyond this point no suggestion worth making can be 

 ofiered. The genetic relations of the Tunicates and the Vertebrates, 

 or between either of these and any worms intermediate between 

 Tunicates and Vertebrates, which may have existed, cannot be 

 spoken of as even probably known. 



§ 9. The foregoing suggestions are offered as results which seem 

 to present themselves to the inquirer into the past history of 

 animal life, and into the cat's iiedigree. 



The next question refers to the cat's origin. This second 

 question refers, as before said, to the probable causes which have 

 determined that process of evolution which has, in fact, taken 

 place. It is a question of causation : It investigates the " how " 

 and the "why" of the origin of the cat's species, and — as we 

 cannot suppose that the cat is different in this respect from other 

 animals — the cause of the origin of species generally. Evidently 

 that cause must lie either within or without the living organisms 

 which are evolved, unless it be partly within them and partly 

 external to them. 



We may conceive the evolution of new specific forms to have 

 been brought about in one or other of the six following ways. 

 The change may have been due : — 



(1) Entirely to the action of surrounding agencies upon organ- 



isms which have merely a passive capacity for being 

 indefinitely varied in all directions, but which have no 

 positive inherent tendencies to change or vary, whether 

 definitely or indefinitely ; 



(2) Entirely to innate tendencies in each organism to change in 



certain directions ; 



(3) Partly to innate tendencies to vary indefinitely in all direc- 



tions, and partly to limiting tendencies of surrounding 

 conditions, which check variations except in such direc- 

 tions as may happen to be accidentally favourable to the 

 organisms which vary ; 



(4) Partly to innate tendencies to vary indefinitely in all direc- 



tions, and partly to external influences which not only 

 limit but actively stimulate and promote variation ; 



(6) Partly to tendencies, inherent in organisms, to change defi- 

 nitely in certain directions, and partly to external 

 influences acting only by restriction and limitation on 

 variation ; 



(6) Partly to innate tendencies to change definitely in certain 



