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T HE following description of a cineradiographic study of breast feeding supplements our previous paper on bottle feeding (Ardran, Kemp and Lind, 1958). The investigations were made concurrently and with the same apparatus.Forty-one infants were examined while feeding at the breast. They were of both sexes and of ages ranging from a few days to several months. METHOD Before the examination the mother's nipple and its surrounding areola were thinly coated with a paste of barium sulphate powder in Lanoline. The baby was laid on a couch so as to obtain films of the head and neck in lateral projection. The mother leaned over the couch with her body twisted so as to allow one breast to project clear of the chest wall. A nurse adjusted the baby to the mother's nipple and when feeding was established the radiographic exposure was made. One cinefilm was taken of each subject (25 frames per second), the exposure limited to approximately four seconds, the dose-rate being about 0-3 r at the skin per 100 frames. Care was taken to make the mother comfortable by adjusting the height of the couch and by providing suitable supports for her arms. In seven individuals the inner and outer margins of the areola were also marked with pieces of tin foil embedded in plastic skin.Four women also had 16 mm colour cinefilms taken to show the infant taking the nipple into the mouth and feeding. Films were also taken of the mother's breast as feeding was interrupted by removal of the child. RESULTS

With 8 plates in the text)The anatomy of the masticatory apparatus, and particularly of the mandibular joints, has led to the view that mandibular movement in the Rodentia is predominantly propalinal, or forwards and backwards in direction. As part of an investigation into the mechanism of function of the mandibular joints in these animals, the feeding behaviour of "August" strain and "Wistar" rats was examined by cinephotography and cinefluorography. The rats were trained to feed on barium sulphate impregnated biscuit and animal cake and to drink radio-opaque liquids. Cinefluorographic recordings of ingestion, mastication, deglutition and of drinking were taken in both the lateral and dorso-ventral projections.Analysis of the recordings has shown a fundamental separation of ingestive and masticatory activity in the rat, which can be attributed to the morphology of the jaws and particularly to the disparity in the lengths of the mandibular and maxillary diastemas. To bring the incisor teeth into occlusion for ingestion, the mandible is brought forward through the rest position and the condyle into articulation with the anterior part of the fossa. In mastication the condyle is moved backwards to bring the molar teeth into occlusion and the condyle into articulation with the posterior articular facet on the fossa. Once the mandible has been moved into the appropriate position for either ingestion or mastication and deglutition, the movements involved in the separation or chewing of the food are cyclical with combined horizontal and transverse movements as well as the fundamental vertical movement acting to open and close the mouth. The basic movement of ingestion carries the mandibular incisors upwards and forwards across the lingual surfaces of the maxillary incisors, so separating the bite. The grinding stroke of mastication is a horizontal movement carrying the mandibular molars anteriorly across the maxillary.