_ ACCLIMATISATION AND BREEDING 211 
pheasants, and Australian black swans are all left out of doors 
throughout the entire winter. The marabou and the ibis 
can stand 10° of frost, and Australian cockatoos, aras, 
etc., do not have to take shelter even when the temper- 
ature sinks to 15° F. It is obvious, however, that there are 
many small tropical birds and mammals which it will never 
be possible to acclimatise. Reptiles and amphibians also 
are difficult subjects, though one never knows what may 
not be done until one has tried. 
As I have already observed, the fundamental law of ac- 
climatisation is to provide as large spaces as possible for the 
animals to roam about in. In Stellingen, moreover, I always 
try to supply an environment which resembles as far as 
possible the natural environment of the animals. I endeavour 
to consider the psychic as well as the physical condition of the 
animal, so that they should forget, if it be possible, that they 
are prisoners at all. The gregarious animals I always keep 
together in large enclosures. This goes a long way towards 
combating the tediousness which is one of the greatest 
difficulties to be overcome in keeping wild animals in captivity. 
Constant association enables them to play about together, 
keeps up the appetite, and maintains the body in a healthy 
condition. There are, therefore, in Stellingen wide tracts of 
meadow-land in which wander animals of many different 
species, though all are provided with shelters in case of un- 
favourable weather. Rocky ranges rise high into the air 
dotted with mountain animals from various parts of the world, 
and ona high plateaua herd of reindeer may be seen. A rock is 
provided, in as exact an imitation as possible of an iceberg, so 
that the polar bears may think that they are still in the Arctic 
regions; and there are great ponds with numerous. shelter 
corners in which seals, penguins, and water birds may feel that 
they are in their own home. . 
Certain other Zoological Gardens have been carrying out 
experiments of the same kind. In the acclimatisation of 
various exotic mammals and birds, Dr. Brandis in Halle has 
ids? 
