The carrying out of digestion experiments with swine introduces difficulties of technique which are not encountered in similar work with sheep. The pig is apt to be restive under restraint and does not always take kindly to the wearing of harness. The designing of a suitable harness is not easy on account of the shape of the pig, and when confined in a metabolism cage, the animal frequently spends much of its time rubbing vigorously against the sides, thereby considerably disarranging the harness. Moreover, since the pig increases in size so rapidly, it is necessary that the fit of the harness be capable of adjustment within wide limits. A further difficulty is connected with the voracious appetite and destructiveness of the pig, so that if the experimental ration does not satisfy the hunger of the animal, the latter will often gnaw the wooden parts of the crate and will even devour its own faeces, if the degree of freedom of movement permits it to turn round. The quantitative feeding of a pig is a matter of difficulty, owing to the animal's eagerness and its habit of stepping into the food trough. Swine do not display such hardiness under confinement as do sheep, and it is therefore necessary to maintain an equable temperature in the metabolism room throughout the experiments.