[45] J. Hunter shows that the long period of seventy-three days given by Buffon is easily explained by the bitch having received the dog many times during a period of sixteen days ('Phil. Transact.,' 1787, p. 253). Hunter found that the gestation of a mongrel from wolf and dog ('Phil. Transact.,' 1759, p. 160) apparently was sixty-three days, for she received the dog more than once. The period of a mongrel dog and jackal was fifty-nine days. Fred. Cuvier found the period of gestation of the wolf to be ('Dict. Class. d'Hist. Nat.,' tom. iv. p. 8) two months and a few days, which agrees with the dog. Isid. G. St. Hilaire, who has discussed the whole subject, and from whom I quote Bellingeri, states ('Hist. Nat. Gén.,' tom. iii. p. 112) that in the Jardin des Plantes the period of the jackal has been found to be from sixty to sixty-three days, exactly as with the dog.
[46] See Isid. Geoffroy St. Hilaire, 'Hist. Nat. Gén.,' tom. iii. p. 112, on the odour of jackals. Col. Ham. Smith, in 'Nat. Hist. Lib.,' vol. x. p. 289.
[47] Quoted by Quatrefages in 'Bull. Soc. d'Acclimat.,' May 11th, 1863.
[48] 'Journal de la Physiologie,' tom. ii. p. 385.
[49] See Mr. R. Hill's excellent account of this breed in Gosse's 'Jamaica,' p. 338; Rengger's 'Saeugethiere von Paraguay,' s. 153. With respect to Spitz dogs, see Bechstein's 'Naturgesch. Deutschlands,' 1801, b. i. s. 638. With respect to Dr. Hodgkin's statement made before Brit. Assoc., see 'The Zoologist,' vol. iv., for 1845-46, p. 1097.
[50] 'Acta Acad. St. Petersburgh,' 1780, part ii. pp. 84, 100.
[51] M. Broca has shown ('Journal de Physiologie,' tom. ii. p. 353) that Buffon's experiments have been often misrepresented. Broca has collected (pp. 390-395) many facts on the fertility of crossed dogs, wolves, and jackals.
[52] 'De la Longévité Humaine,' par M. Flourens, 1855, p. 143. Mr. Blyth says ('Indian Sporting Review,' vol. ii. p. 137) that he has seen in India several hybrids from the pariah-dog and jackal; and between one of these hybrids and a terrier. The experiments of Hunter on the jackal are well known. See also Isid. Geoffroy St. Hilaire, 'Hist. Nat. Gén.,' tom. iii, p. 217, who speaks of the hybrid offspring of the jackal as perfectly fertile for three generations.
[53] On authority of F. Cuvier, quoted in Bronn's 'Geschichte der Natur,' B. ii. s. 164.
[54] W. C. L. Martin, 'History of the Dog,' 1845, p. 203. Mr. Philip P. King, after ample opportunities of observation, informs me that the Dingo and European dogs often cross in Australia.