1. In order to study the excitation conduction between cardiac muscle and vascular muscle in venae cavae, the transmembrane action potentials and the unipolar surface electrograms were recorded simultaneously from the atriocaval preparation isolated from a rabbit.
2. The impulse which originates in the sinus node spreads not only to the atrial muscle but also to the vascular muscle in venae cavae (sino-caval conduction).
3. Sino-caval block was frequently observed to occur under the condition where sino-atrial block was not observable.
4. The transmembrane action potential with a hump on the upstroke was recorded from the region of the transition from the fibers of the sinus node to those of the right superior vena cava. After a prolonged period of experiment, the hump became prominent and the spike was frequently extinguished leaving only a small potential.
5. From the mode of appearance of small potentials and notched action potentials, it is suggested that the vena caval margin of the sinus node presents obstacles to smooth passage of excitation and that thus sino-caval conduction is more easily and more markedly depressed than sino-atrial con-duction under some poor conditions.

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1. Single muscle fibres isolated from the claw adductor of the crayfish were stimulated directly by transversely applied rectangular current pulses and the resulting contractions were studied.
2. The height of tension response increased with the increase in the intensity of the current at constant duration or with the increase in the duration of the current at constant intensity, and reached a plateau in both cases.
3. The behaviour of suspended fibres in response to a brief pulse and the algebraical summation of tension response by two brief pulses of opposite sign have shown that the contraction elicited by a brief pulse is confined to the cathodal side of the fibre.
4. On the other hand, the whole fibre could be made to contract uniformly by a prolonged current pulse or a series of repetitive brief ones of sufficient intensities. This may be taken to indicate that the membrane depolarization around the whole fibre surface may not be necessary to bring the whole fibre to contract uniformly.
5. Using two pulses of same sign, it was possible to examine the summation of contraction up to the shortest interval without involving the summation of depolarization.
6. From these results it is concluded that the increase in the number of activated myofilaments may be involved in the process of summation by two pulses of same sign. The possible mechanism of the gradation of contraction in crustacean muscles was also discussed in this connection.

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Methods for continuous recording of cutaneous perspiration in a small area of the skin were reported. In the methods, desiccant material provided in an absorption capsule absorbs water vapour from the skin covered with the capsule. The volume of water absorbed in the desiccant was recorded as the increase of weight (gravimetric method) or as the increase of electrical conductance (electrical conductance method) of the desiccant material. In the gravimetric method, the weight increase was converted into movement of light spot on a distant scale, and finally, by means of manual procedure using a sliding apparatus, into unbalanced potential of a bridge circuit. In both methods, the changes of electrical measures were registered directly (integral values) or as differential values using a device for differentiation circuit. Differential values were obtained as spike deflections, height of which represents the rate of water evaporation in 20 seconds. Examples of the results of application on human body were demonstrated for both methods.

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1. The activity of cardiac vagal efferent fibers was observed in fine strands obtained by splitting the cervical vagus of the dog anesthetized with morphine, chloralose and urethane. The responsiveness to sinus nerve stimulation was used as a criterion for identification of cardiac fibers.
2. The conduction rates of cardiac vagal fibers ranged from 4 to 12 m/sec, averaging about 8 m/sec.
3. Most cardiac vagal fibers were spontaneously active. Both spontaneous and reflexive discharges were inhibited during the inspiratory phase of spontaneous respiration.
4. The reflex discharge of a cardiac vagal fiber to sinus nerve stimulation was non-specifically inhibited when either the vagus, sciatic, brachial or saphenous nerve was simultaneously stimulated.

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1. The effect of temperature on the integrated response of the whole glossopharyngeal nerve of the frog was investigated, by varying temperature of solutions and by using the method of the preadaptation.
2. A maximum magnitude of the response to NaCl was evoked at the temperature between 20°C and 25°C and the rate of the increase of the response with an increase in concentration was greatest at 20°C or 25°C.
3. CaCl₂ produced a maximum magnitude of the response at 20°C regardless of the concentration. The magnitude of the response to distilled water and 0.1 M sucrose also revealed a maximum at 20°C.
4. The optimum temperatures in the response to quinine and to AcOH varied with the increase in concentration from 20°C to 30°C and from 25°C to 30°C, respectively.
5. Off-responses were observed when the tongue was rinsed with 0.01 M NaCl solution after the stimulation with AcOH. They were dependent on the concentration of AcOH and showed a similar temperature dependency to AcOH.
6. Some variation of the optimum temperature for the NaCl response by changes in the ambient temperature was noticed, the seasonal difference of the optimum temperature being suggested.

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1. The effect of temperature change on the chorda tympani response of the cat has been investigated, by carrying out the stimulation of the tongue by NaCl, KCl, HCl and quinine at varying temperatures.
2. The greatest response magnitude was obtained at 30°C for NaCl, HCl and quinine, while the response to KCl showed a maximum magnitude at 35°C.
3. The Q₁₀ values for NaCl and KCl stimulation were small compared with those for HCl and quinine. A possible significance of this result for the mechanism in receptor-substance reaction was discussed.
4. The thermal responses in both the chorda tympani and the lingual nerve to temperature change of the tongue were described.

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This paper deals with voltage clamp experiments on the single plant cell. Nitella axillaris give membrane currents (after step changes of membrane potential) that are very similar to those of the squid giant axon except that they are much slower and smaller. For depolarizations of 20-60 my a transient inward current is followed by a steady outward current. For larger depolarizations, the steady outward current sets in during the flow of the transient inward current. The vacuolar potential at which the transient inward current does not appear, or turns to become outward, is 40-60 my positive to outside. For increasing hyperpolarizations only increasing inward currents are observed. The resistance of the membrane at rest is estimated to be 250 kΩ. cm² for hyperpolarization and 20 kΩ. cm² for depolarization. The minimum resistance calculated from the peak transient inward current is 4 kΩ. cm2.
An increase of outside chloride concentration to 10 mM reduces the maximum transient inward current by 40 per cent. An increase of outside calcium concentration to 10 mM, with constant Cl concentration, produces only a small decrease of the transient inward current, while the durations of the inward current and the action potential are usually increased. It is concluded that the ion responsible for the normal electrophysiological activity of the cell may be mainly chlorine ion rather than calcium ion.

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The physiological characters of the sensory nerves from the submandibular gland were studied.
In a preliminary experiment on a human sub ject, sensations which were induced by application of a back-pressure to the submandibular duct was evaluated. A swollen sensation was felt in the sublingual area of the floor of the mouth at 60 mmHg pressure, and pain localized in the submandibular gland region was elicited at 90 mmHg.
The main experiments were on anesthetized dogs. A small tube was inserted into the duct of the submandibular gland and this was connected to a balloon pump (pressure pump) and to an electric manometer. To stimulate ordinary salivary secretion 1% pilocarpine (0.02 ml/kg) was injected intravenously, and in some experiments a back-pressure was also applied to the gland. The pressure curves and electrical activities of single fibers of the submandibular branch of the chorda tympani nerve were recorded simultane-ously.
During salivary secretion induced by pilocarpine and during application of a back-pressure to the duct, the electrical activity of certain fibers in the submandibular branch of the chorda tympani was markedly facilitated following increase in internal pressure in the gland.
There were found to be two types of baro-receptive fibers in the submandibular branch of the chorda tympani. One was the type which showed a slow adaptive response and the discharge of this type increased with increase in the ductal pressure. The other type showed a fast adaptive response and responded only to a certain definite level of internal pressure in the duct.
These results suggest that baro-receptors in the ductal structures of the salivary gland may send information about the state of ductal dilatation during salivary secretion.

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1. The effect of zinc on the membrane properties of frog skeletal muscle fibre was investigated with intracellular microelectrode. And the relationship between the change in membrane properties and the twitch potentiation was studied.
2. The resting potential was not affected by the presence of zinc less than 2.5 mM. This small amount of zinc did not affect the potassium conductance of resting muscle membrane.
3. In the presence of 0.5 mM zinc, the specific membrane resistance increased from 3700 Ωcm² to 10400 Ωcm², space constant from 1.9 mm to 3.0 mm, time constant from 14.7 msec to 35.7 msec, while the membrane capacitance underwent little or no change. The membrane resistance increased almost linearly with the logarithmic concentration of zinc in the range 0.05 mM to 0.5 mM, but no more increase was observed at higher concentration than 0.5 mM. This resistance increase was attributed to the decrease in chloride conductance.
4. The increase in the effective duration of action potential was clearly detected in the presence of 0.0025 mM zinc, and reached the maximum at 0.5 mM. The main cause of this increase is the slowing of the falling decay of action potential due to the reduced potassium conductance of active membrane by zinc.
5. The twitch tension was potentiated approximately in proportion to the logarithm of the zinc concentration in the range 0.0025 mM to 0.05 mM, and the manner of per cent increase in it was quite similar to that of the effective duration of action potential in the above described range. There was no such parallel relation between twitch potentiation and increase in membrane resistance.
6. The sequence for the twitch potentiation by zinc was discussed. The twitch tension seems to be potentiated by the prolongation of action potential, but the contraction process could not follow immediately this prolonged depolarization until the excitation-contraction link will be matched with it by the facilitatory effect of zinc on the link.

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