Chap. XVIII. CHANGED CONDITIONS. 149 



refuse to breed in captivity. Isidore Geoffroy St. Hilaire 9 

 consequently has drawn a broad distinction between tamed 

 animals which will not breed under captivity, and truly domes- 

 ticated animals which breed freely — generally more freely, 

 as shown in the sixteenth chapter, than in a state of nature. 

 It is possible and generally easy to tame most animals; but 

 experience has shown that it is difficult to get them to breed 

 regularly, or even at all. I shall discuss this subject in detail ; 

 but will give only those cases which seem most illustrative. 

 My materials are derived from notices scattered through various 

 works, and especially from a Eeport, drawn up for me by the 

 kindness of the officers of the Zoological Society of London, 

 which has especial value, as it records all the cases, during nine 

 years from 1838-46, in which the animals were seen to couple 

 but produced no offspring, as well as the cases in which they never, 

 as far as known, coupled. This MS. Report I have corrected 

 by the annual Reports subsequently published. Many facts are 

 given on the breeding of the animals in that magnificent work, 

 ' Gleanings from the Menageries of Knowsley Hall/ by Dr. Gray. 

 I made, also, particular inquiries from the experienced keeper 

 of the birds in the old Surrey Zoological Gardens. I should 

 premise that a slight change in the treatment of animals some- 

 times makes a great difference in their fertility; and it is 

 probable that the results observed in different menageries would 

 differ. Indeed some animals in our Zoological Gardens have 

 become more productive since the year 1846. It is, also, mani- 

 fest from F. Cuvier's account of the Jardin des Plantes, 10 that 

 the animals formerly bred much less freely there than with us ; 

 for instance, in the Duck tribe, which is highly prolific, only one 

 species had at that period produced young. 



The most remarkable cases, however, are afforded by animals kept in 

 their native country, which, though perfectly tamed, quite healthy, and 

 allowed some freedom, are absolutely incapable of breeding. Eengger, 11 who 

 in Paraguay particularly attended to this subject, specifies six quadrupeds 

 in this condition; and he mentions two or three others which most rarely 



* < Essais de Zoologie Generale,' 1841, « « Saugethiere von Paraguay,' 1830, 



P 'in £ t, l , * , ,- , 8.49,106,118,124,201,208,249,265, 



10 Du Put, 'Annales du Museum,' 327 



1807, torn. ix. p. 120. 



