THE LENGTH OF ANIMAL LIFE AT THE ZOO 177 



cold fogs incident to the undrained clay by which 

 they are surrounded in Regent's Park a pregnant 

 but happily remediable source of ill-health even to 

 its human inhabitants.' The park was drained in 

 1851, with marked results in improving the health 

 of the animals at the Zoo. Experience also was 

 not thrown away. Fifty years ago, when lion-keep- 

 ing was in its experimental stage, the records of the 

 Society showed that lions, leopards, tigers and pumas 

 lived, on an average, for two years only in the 

 Gardens, which gave a rate of mortality of about 

 one per month. They were then confined in small 

 stuffy cages, artificially heated throughout the year. 

 They were transferred to cages, now occupied by 

 the bears, in which no artificial heat was supplied at 

 all, with greatly improved results. The fine new 

 lion house, in which they have warm winter quarters, 

 with an open summer garden attached, answers 

 admirably, and the records of mortality seem to 

 give some clue to the natural length of life of 

 species. Lions, for instance, live on an average for 

 fifteen years, tigers for eleven, and leopards for eight 

 years. 'Duke,' the old lion recently dead, was we 

 speak from memory eighteen years old. The oldest 

 living lioness was brought to the menagerie in 1877. 

 With a curious coincidence of name, the Patagonian 

 sea lion is sixteen years old, and though it shows 



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