FOREWORD 3 
except the intangible reward appreciated only by the real 
research worker. 
It is a mistake to think that all animals in the wild 
state are healthy. The healthy wild animals that we see 
are the survivors, the sick and the weaklings having died. 
Undoubtedly diseases are fewer than in captive animals ; 
but on the other hand wild animals are exposed to dangers 
to which captive animals are not exposed — such as lack of 
care in sickness and old age, starvation, and attacks of 
enemies that feed on them. The maximum longevities in 
some species are probably in captive animals. It is doubt- 
ful if a wild animal ever reaches the greatest age 
possible to it. 
Many kinds of parasites have been found in wild 
animals captured only a short time before arriving at the 
Garden, so that they must have existed in the wild. Thir- 
teen wild cats received from South Carolina within a few 
days after capture were infested with intestinal, muscu- 
lar, and pulmonary parasites. Several years ago there 
were received from the Island of Chincoteague, off the 
coast of Virginia, a number of native birds recently cap- 
tured, all of which had mould disease of the air sacs. 
This happened on several occasions, so that it became 
necessary to reject all birds from this locality. Among 
the birds were meadow larks and cardinals. 
Hunters not infrequently kill animals with disease, 
and if more hunters knew enough to recognize the disease 
there would be more recorded cases. Sick animals are not 
as likely to be killed by the hunter as healthy ones, as sick 
animals seek seclusion and do not move about. In many 
localities of the United States white-tailed deer are 
infested with the liver-fluke. Trout and other fish in 
remote mountain streams are found with tapeworms. 
Round worms and other parasites infest the white 
rhinoceros in the African forest. 
