The static and the dynamic characteristics of the neuron in impulse frequency to temperature stimulation were formulated in reference to the experimental data of the crayfish stretch receptor and Aplysia neurons. Physiological mechanisms which explain the meanings of the formulation were discussed in relation to the membrane process of the neuron. Constructing the analogue computing circuit which realizes the formulated characteristics, neuron responses to the temperature stimulation of various wave forms were simulated. Further, on the assumption that the above formulation is also valid for the subthreshold on impulse generation of the neuron, the eccentric transient responses of the neuron to temperature stimulation were simulated in impulse trains by using a v-f converter.
These were newly obtained results by the present formulation of temperature responses of the neuron, and would serve for bio-engineering researches concerned with the temperature effects on the neuron.

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Physiological and hydrodynamic experiments were carried out in order to evaluate comprehensively and systematically the hemodynamics of the cardiovascular system in the dogs. A sinusoidal flow pump which perfuses controlled blood flow into the aorta, pulmonary artery and the peripheral arteries with various frequencies ranging from 0.01 to 30 Hz was designed to measure the pressure to flow relationships versus hydraulic frequency. The results obtained from the experiments are summarized as follows :
(1) Cardiovascular system dynamics was investigated from the view point of circuit theory through the experiments in which the left ventricle of a dog's heart was loaded with the polyvinyl tube and pressures and flows were measured.
(2) By perfusing the arterial systems with the pump, the static and dynamic characteristics of blood pressure and flow were investigated and the linearity of the hydrodynamic functions of the vascular systems was discussed.
(3) The frequency characteristics of the hydraulic input impedance measured at the aortic root showed inherent pattern, the analytical study of which led to the conclusion that the impedance functions at low frequency mainly depended on the aortic compliance and total peripheral resistance, but that, at high frequency, on the peripheral organic load impedances.
(4) The effects of chemical agents on the circulation were also discussed by measuring input impedances of the systemic circulation.
(5) A comparison study between the systemic circulation and the hydrodynamic model system was carried out successfully; based on the results, the effects of chemical agents, fluid viscosity and aortic compliance on the circulation were discussed.
(6) Cardiovascular system was evaluated as the Windkessel model and the theoretical study of the systemic circulation and the peripheral organic circulation was carried out applying the principle of superposition of the system.

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In order to estimate the accuracy and response time of the deep body thermometer, presented by R. H. Fox and A. J. Solman, a simulator experiment was carried out. The transducer probe of the thermometer was improved to such an extent that the circumference of the probe could be warmed up to the same temperature as the center. In the simulator experiments, heat conducting layers of varying thickness were inserted between the transducer and a constant temperature copper plate. As a result, the deep temperature could be measured on the surface of a rubber layer of 9 mm t at an accuracy of 0. 1°C. The response time of the 9 mm rubber layer was about 20 min. The thermometer was also applied to human subjects, and the temperature response proved similar to the case of the simulator experiment of 6-9 mm rubber layer. From these results, it was confirmed that the thermometer could be applied to deep body temperature measurements with an accuracy of 0.1°C.

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