Van Wagenen, G. 1950. The monkeys. In: The Care and Breeding of Laboratory Animals . Farris, E. J. (ed), 1-42. John Wiley, New York, NY.

Valuable observations regarding the space requirements of single-housed rhesus macaques. It is inconceivable that growing monkeys in the laboratory be denied their essential activities of swinging, jumping, and scampering about. This calls for space. ... If sufficient room is not provided, some males will soon show depression, sitting quietly in the part of the cage which affords the best view. For a while this may be interpreted as an adaptation. ... Too often, however, this persistent posture apparently results in a pressure atrophy, bringing on a lower-limb palsy, the so-called 'cage paralysis'. ... Sitting on the board [approximately 1 m off the ground of the room], facing the center of the room, is the favorite position of the monkeys. At this height these intensely alert animals have a better view of activities within the room, and they can meet visitors on the same eye level. ... and they sleep on the board at night.