THE VEGETABLE AND ANIMAL KINGDOMS. 141 



should refuse to bear seed by the one which has departed 

 most widely, and yet produce it readily by another, which 

 still agrees with it in some important points." ( ;0 ) Admit this, 

 and the grand basis of specific distinction, the possibility of 

 intermixture, can no longer be laid hold of. Plants and 

 animals of one line are only to be expected to unite, which, 

 being of one grade of organization, are also sufficiently near 

 to each other in those peculiarities liable to modification from 

 external causes, on which the so-called distinctions of species 

 are grounded. 



The illustrations of our hypothesis are now closed. We 

 have seen that, even judging from short spaces of time, there 

 is a great and incontestable modifiability of organic forms, so 

 great as to have absorbed the presumed distinctions of species 

 in many noted instances. We have seen that this modifi- 

 ability, by some hidden law, immediately obeys external con- 

 ditions. It has also been seen that, though no transition 

 from grade to grade was ever observed to take place, the 

 means and mode by which it could naturally happen are not 

 concealed from us ; they are pictured before our eyes in the 

 metamorphosis of the tadpole, and even practically exem- 

 plified in a narrow degree in the natural history of the bee. 

 It has been shown that no organism is independent, but all 

 stand in a web of intimate relation, undeniably indicating 

 that their origin is one connected phenomenon. It has been 

 seen that the higher animals, when their organization is ex- 

 amined, are only improvements upon the lower advanced 

 forms of the same beings ; and the same holds good regarding 

 plants. In conformity, too, with this gradation of forms, is 

 the succession of the actual animals throughout the geological 

 ages ; a fact most important not merely one calling to be 

 explained, as is at the utmost allowed by men of science of 

 the present day, but one which helps to explain, a piece of 

 actual tangible evidence, and bearing wholly, when taken in 

 connexion with proofs of other kinds, in favour of the 

 natural origin of species. Surely when, in addition to all 

 this, we learn that life is believed by many men of science to 

 spring occasionally, even now, from inorganic elements 



