Dr Morton on Hybrid Animals and Plants. 271 



his doctrine, have been developed by the mere force of cir- 

 cumstances, — a tendency to progressive advancement from the 

 simplest to the most perfect forms. And here we may in- 

 quire, — If education and domesticity can so vary not only the 

 instincts but the very proportions of anatomical structure in 

 dogs, do we not realize in the theory of Lamarck, a law of 

 nature which would, with equal readiness, explain the un- 

 limited transmutation of species into each other ? 



But is it proved that all the domestic dogs are really de- 

 rived from a single species \ Here again we appeal to one of 

 the latest and best authorities on this question — Charles 

 Hamilton Smith, whose laborious researches have led him to 

 the following conclusions — that the parents of our domestic 

 dogs are derived from several distinct species, which were 

 constituted with faculties to intermix, and thus to produce 

 the interminable varieties familiar to man ; that five of these 

 types belong to the Old World alone, viz., the wolf, the buansu, 

 the anthus, the din^o, and the jackal ; that a dhole or a thus 

 may have been the progenitor of the greyhound ; and that 

 the origin of the primitive mastiff may yet be traced to a lost 

 or undiscovered species belonging to the hyena tribe.* 



The wolf, the dog, the jackal, and the fox, all intermix 

 with each other. So does the common jackal with thfe jackal 

 of Senegal. Do they therefore belong to one species I It is 

 well known that the cross between the dog and the European 

 wolf in the experiments of Buffon, did not extend beyond the 

 fourth generation ; but the distinguished writer whom we 

 have just quoted, has observed, that the animals were in a 

 state of neglect and restraint, and gradually tended to steri- 

 lity, from their small number, and from the want of recross- 

 ings from one or other of the parental stocks. It is worthy 

 of remark, that the din^o of Australia when placed in simi- 

 lar circumstances with the common dog, also becomes steril 

 in the fourth generation ; whence, according to this test, the 

 din^o is not a true dog, ])ui some other species of the genus 

 Canis. 



* Natural History of the Dog, in Naturalist's Library, vol. i., p. 104, et paS' 

 aim. The Cants venatica of Burchell, connects the dog with the hyena almost 

 without an Uiterval. 



