27Z 



THE QUARTERLY REVIEW OF BIOLOGY 



MORTALITY IN ZOOLOGICAL GARDENS 



But while ideal material for compara- 

 tive pathology is thus lacking, there is 

 available a body of records which can be 

 utilized to throw some light on our prob- 

 lem. I refer to the autopsy records 

 made in large zoological gardens. The 

 important conditioning factors regarding 

 such records from a biometric point of 

 view are these: 



a. The population of a zoological gar- 

 den is composed of wild animals. But 

 in this population the different natural 

 orders are not necessarily or actually repre- 

 sented in proportion to the frequency with 

 which individuals belonging to these 

 orders occur in a state of nature. The 

 population is a selected one, the basis of 

 the selection being primarily the behavior 

 and longevity of the individuals in cap- 

 tivity, and their interest to human beings 

 as objects of display. This artificial 

 character of a zoological garden popula- 

 tion means that deductions regarding 

 mammals as a group, or birds as a group, 

 must always be subject to the reservation 

 that the samples are not completely 

 representative. 



b. The animals are in a state of cap- 

 tivity, artificially and regularly fed, in 

 accordance with what human beings, on 

 an insufficient basis of knowledge, suppose 

 to be their needs and desires. That these 

 conditions alter the whole natural and 

 normal biological picture, including its 

 pathological aspects, admits of no doubt. 

 To paraphrase Dr. Johnson's remark about 

 the performing dog the wonder is not that 

 the animals live as well as they do in 

 zoological gardens, but that they live at 

 all under such unnatural circumstances. 



c. In most zoological gardens complete 

 and careful post-mortem examinations 

 are not made of all the animals that die, 

 and the results of such examinations as are 

 made are not published in detail. An 



outstanding exception to the latter state- 

 ment is furnished by the thorough and 

 painstaking work of Fox (Y) and his assist- 

 ants at the Philadelphia Zoological Gar- 

 den. Here a trained pathologist has taken 

 the work seriously and amassed a col- 

 lection of records of great interest and 

 value. It is unfortunate that the statis- 

 tical presentation of the records in the 

 monumental report cited falls, in some 

 respects, below the high level of excel- 

 lence of the pathological work itself. 



While these factors distinctly limit the 

 usefulness, for the present purpose, of 

 these records of deaths in zoological 

 gardens, it is desirable to examine some 

 of them briefly. In a comprehensive 

 study of the biology of life duration and 

 death any and all evidence, however frag- 

 mentary, should be brought under review. 



DATA FROM THE LONDON ZOOLOGICAL 

 GARDEN 



From a biometric point of view the 

 statistics of deaths in the Garden of the 

 Zoological Society of London, are the 

 most satisfactory. Their outstanding 

 merit is that they account, in some way 

 or other, for all the deaths occurring 

 within a given year. The record is 

 statistically complete. It is in this re- 

 spect that the death records from the 

 National Zoological Park in Washington, 

 published in the Annual Reports of the 

 Smithsonian Institution, fail. In a quite 

 erratic way they leave a considerable 

 number of deaths unaccounted for. 



The present paper is based upon the 

 statistics from the London Gardens for 

 the four years 1910 to 192.3 inclusive, as 

 published by N. S. Lucas, M.B., F.Z.S. 

 (4-7), the pathologist to the Society dur- 

 ing the years named. 



In these four years 4,448 deaths in total 

 were reported. Of these 3,150 were re- 

 corded by causes, as determined by 



