Posture and heart rate in the domestic hen

Synopsis When unanaesthetised fowls were hung upside down on shackles the heart‐rate immediately rose by about 30 per cent; on re‐inverting them after 2, 4 or 6 min it returned rapidly to normal. It behaved similarly in anaesthetised birds save that the response to inversion was somewhat smaller and slower, depending on the depth of anaesthesia, and there was some over‐compensation before return to normal. It is concluded that the effect was probably a response to changes in the activity of baroreceptors in the cardiovascular system and that the data do not disclose evidence of serious distress.