Wasserthal, L.T. (1980): Oscillating haemolymph ‘circulation’ in the butterfly Papilio machaon L. revealed by contact thermography and photocell measurements. - J. Comp. Physiol. 139: 145-163.
1. Pulsating and streaming of haemolymph in the heart, aorta and perineural sinus of unrestrained, unnarcotized Papilio machaon L. (Lepidoptera, Papilionidae) were studied. The interrelationships between heart activity, abdominal movements and activity of thoracic pulsatile organs in haemolymph transport were examined and the indirect effects of these activities on tracheal ventilation of the thorax evaluated. 2. A thermistor technique was developed to record haemolymph movements by their convective and conductive cooling effects at the cuticular surface of insects. In addition, the direction of pulses and of haemolymph flow was determined from temperature measurements, utilizing the temperature gradient along the body axis of basking butterflies. 3. The direction of heart peristalsis changes periodically and is coordinated with abdominal length changes which were recorded using a photocell. Abdominal expansion is accompanied first by a pause and subsequently by reverse beating of the heart. Abdominal expansion may play a leading role in backward haemolymph transport and cause periodic ventral haemolymph backflow through the perineural sinus. Such backflow is most vigorous during heart pauses. The rhythmic undulatory movements of the ventral diaphragm give rise to only slight thermal convective effects. 4. The oscillation of haemolymph between thorax and abdomen is documented on the basis of changes in thermal conduction of the thorax. The significance of periodic haemolymph volume reduction in the thorax for tracheal ventilation is discussed with special regard to the role of heartbeat reversal. 5. During the forward heart pulse periods the abdomen performs volleylike ventilatory movements. These do not cause streaming of haemolymph in the thoracic haemocoel, which at this time is shut off from the abdominal haemocoel by a valve mechanism. This valve, situated in the anterior abdomen, was examined histologically and by scanning electron microscopy. 6. The activity of the lateral thoracic pulsatile organs is regularly interrupted by pauses which occur most frequently during the second half of the heart's forward pulse period. The function of the pulsatile organs is discussed in relation to changing thoracic haeraolymph content.

P.machaon oscillatio