THE VEGETABLE AND ANIMAL KINGDOMS. 139 



the stars at the rate of two millions of millions of miles a year ; 

 but astronomers tell us that it would take ninety millions of 

 years to enable us to pass through the whole, even at this 

 rapid rate. Well, therefore, might the unassisted eye and 

 unexamining intellect presume the place of the solar system to 

 be fixed, for it is evident that no human tradition could 

 record changes indicating the translation. Yet we do pass 

 on to Hercules, although forty centuries failed to remark the 

 circumstance. So may specific distinctions in the higher 

 animals have been changed in the course of the vast periods 

 which geology shows to have elapsed since the commence- 

 ment of organization upon earth, although, during that inap- 

 preciable segment of the great cycle which has passed since 

 man woke to the mysteries of nature, no single transition of 

 the kind might have been observed. The whole case reminds 

 us greatly of the objection which stood against the earth's 

 motion from the days of Aristarchus downwards, that there 

 ought in that case to be an observable parallax. As there 

 was no observable parallax, because the earth's orbit is an in- 

 significant space in comparison with the distance of the stars, 

 so is our observation of animal changes insufficient to show 

 transitions of species in the higher grades of the kingdom, be- 

 cause it is a mere span in comparison with the vast ages 

 actually concerned in the phenomenon. 



A similar principle of explanation applies to the alleged 

 tendency of variety to be obliterated. While it is only to be 

 expected that a single animal showing an originality of form 

 will fail to impress it on its posterity, if it be absorbed in alli- 

 ance with animals possessing no such peculiarities, there is no 

 reason to believe that a variety uniting with a creature like 

 itself will not have descendants of its own character. We 

 judge on this question in the midst of a fully-peopled world; 

 but we must cast back our minds to a time when it was only 

 in the course of being filled with living things. We must 

 think of a time when, for example, over large portions of the 

 surface mountain tracts were rising, perhaps beside low and 

 marshy grounds, or when forests began to spread over exten- 

 sive regions. Here a new field of existence is presented. 



