1869.] DAWSON— IDEAS OP DERIVATION. 133 



posite to those employed by breeders for their purposes. 



(2) Even if we include, along with the struggle for existence, the 

 action of all conditions, favourable and unfavourable, tending to 

 change, we fail to find any evidence of this other than the 

 formation of varieties and races. True species, no longer 

 capable of interbreeding, have not been observed to be produced. 



(3) Though it is conceivable that species may have been produced 

 during the lapse of time, yet even this is rendered improbable by 

 the enormously long periods which Mr. Darwin himself 

 admits to be necessary, and which seem to overgo the possibility 

 of the existence of the creatures in question as far back in 

 geological time as the theory demands. 



(3.) Owen desires to substitute for the above views " an 

 innate tendency to deviate from the parental type operating 

 through periods of adequate duration." According to this 

 hypothesis " a change takes place first in the structure of the 

 animal, and this when sufficiently advanced may lead to 

 modifications of habits." It is difficult to understand this as 

 anything more than a mere statement of a belief in derivation as 

 a fact. It seems to mean that species change because they tend 

 to change. We may add to this if we please that they change 

 independently of external circumstances, and by virtue of a 

 creative plan embodied in them, or rather in the matter of which 

 they are composed ; for Prof. Owen appears to stretch his theory 

 so far as to assert the formation of species spontaneously from 

 inorganic matter, thus giving us the additional thesis that species 

 tend to be before they actually exist. It is also to be observed 

 that the tendency to change, though not caused by external 

 circumstances must act in unison with physical changes, otherwise 

 it would be worse than useless. Taking the case of the Hipparioa 

 and horse, Lamarck would inform us that the former endeavoured 

 to accommodate itself to drier and harder ground, and thus 

 changed the character of its feet. Darwin would say that as the 

 ground became harder those individuals which had the most equine 

 feet would succeed best in the struggle for existence. Owen 

 very properly demurs to both views, holding that there were dry 

 and wet places suitable for horses and Hipparia both in the 

 Miocene and Modern periods, and that the increase of dry ground 

 would merely limit the range of Hipparia and not produce horses ; 

 but he holds that the Hipparia changed into horses merely 

 because they tended to do so, and that if the change suited the 



