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Ch. XXXIV.] 



TEAXSMUTATION OF SPECIES. 



253 



animals 



exposed to tlie danger of being devoured by lions, tigers, and 



compelled to exert tbemselve 



in running with great celerity ; a liabit wbich, in the course 

 of many generations, gave rise to the peculiar slenderuess of 



forms 



The giraffe was not gifted with a long flexible neck be- 

 cause it was destined to live in the interior of Africa, where 

 the soil was arid and devoid of herbage ; but, beino- reduced 

 by the nature of that country to support itself on the foliao-e 

 of lofty trees, it contracted a habit of stretching itself up 

 to reach the high boughs, until its neck became so elongated 

 that it could raise its head to the height of 20 feet above the 



ground. 



Another line of argument was then entered upon, in 

 further corroboration of the instability of species. In order 

 it was said, that individuals should perpetuate themselves 

 unaltered by generation, those belonging to one species 

 ought never to ally themselves to those of another • but 



amon 



animals ; and though the offspring of such irregular connec- 

 tions are usually sterile, yet such is not always the case. 

 Hybrids have sometimes proved prolific, where the disparity 

 between the species was not too great ; and by this means 

 alone, says Lamarck, varieties may gradually be created by 

 near alliances, which would become races, and in the course 

 of time would constitute what we term species.* 

 After explaining his reasons for believing in the soundness 



+ K r\ ^ ^^.^ - 1 T • /^ .* 



of the 



uments 



next proceeded to enquire what were the original types of 

 form, organisation, and instinct, from which the diversities 

 of character, as now exhibited by animals and plants, were 



derived ? We 



said he, that individuals which 



are 



same 



could be traced back far enough, terminate in a single stock ; 



same 



family 



* Phil. Zool. p. 64. 



