Observations of sucking behavior were made on puppies fed (a) by dropper, (b) by bottle, and (c) by the mother. Those nursed by the bitch did not show a significant amount of nonnutritive sucking from the sixth day after birth, while puppies fed by dropper and bottle showed longer, more intense nutritive sucking, as well as considerable nonnutritive sucking. When the dropper-fed and bottle-fed puppies were returned to the mother, nonnutritive sucking diminished considerably. Ross concludes that 'the concept of sucking "deprivation" is a meaningful one in the neonatal behavior of puppies. The results support the notion that a sucking need exists which if not satisfied yields excess nonnutritive sucking.'