Abstract
In the investigation of the problem of experimental neurosis in animals, one of the possible causative factors to be considered is restriction through habituation of the animal's freedom of movement. As an approach to this part of the problem, a study of the animal's spontaneous activity previous to any restriction becomes pertinent.
Experimental neurosis in the sheep leads to a permanent state of hyperexcitability with loss of formerly established discriminations. 1 In the dog the neurosis may manifest itself in chronic somnolence or in hyperexcitability during the conditioning tests. 2 It is reasonable to suppose that the absence of the enduring somnolent or inhibitory experimental neurosis in the sheep may be related to the fact that the sheep does not sleep as the dog does. The pig is a sound sleeper and for this reason it was decided to compare the diurnal cycles of spontaneous activity in these sleeping and non-sleeping animals.
The subjects for investigation were 10 sheep, of both sexes, ranging in age from 1 1/2 to 8 years, and 5 pigs from the same litter, 14 months old, 3 females and 2 males, one castrate. The sheep and male pigs ran in a 15-acre pasture while the sows were limited to a one-acre field. Each of the animals wore a standard New Haven pedometer attached to a harness. They had all become thoroughly habituated to the harness before any records were taken. The pedometers were read twice daily, at 6 A. M. and 6 P. M. Readings were continued for a period of 16 days, from October 15 to October 31. At this season of the year, the intervals between readings corresponded closely to the actual hours of daylight and darkness.
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