1. Gustatory stimulatory characteristics of various salts and several nonelectrolytes were studied in the carp by recording integrated electrical responses from the whole palatine nerve supplying the taste receptors on the palatal organ.
2. In low concentration, the chemoreceptors do not display a sensitivity which shifts progressively with progressive variation in salt concentration. The same is true of the response to most non-electrolytes. Salt solutions in medium concentration were found to depress rather than to stimulate chemoreceptor activity. The degree of depression varied according to the kind of salt. The inhibitory phenomenon of chemoreceptor activity was noted with. non-electrolytes as well. For salts, the greatest stimulating effectiveness was at concentrations specific to a given salt.
3. Comparison of the response-concentration curves for various salts revealed that the difference in stimulating effectiveness of a salt over wide concentration range probably depends on the anion rathr than the cation.
4. Stimulatory characteristics of several non-electrolytes containing different numbers of polar groups in their molecules were compared.
5. Application of distilled water following previous adaptation to the salt solution at the concentration where chemoreceptor activity was depressed elicited a remarkable stimulatory response (“distilled water effect”). No such effect was observed as long as the receptors were responsive to the salt solution previously applied. A similar effect was observed with non-electrolytes. The mechanism involved in the distilled water effect is discussed.

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In order to investigate effects of afferent discharges from muscle spindles, upon EEGs of the neocortex and hippocampus, succinylcholine (Sch) was administered intravenously in 25 cats immobilized with Flaxedil on the basis of previous reports that Sch affects muscle spindles and produce profuse afferent discharges of group Ia and group II fibers at the doses at which neither its. direct effect upon the spinal cord nor upon receptors in the skin was observed.
1. EEG synchronization in the neocortex and irregular slow waves in the hippocampus were usually observed 20-40 min. after Flaxedil (2-4 mg/kg) administration and it lasted for 60-90 min.
2. When Sch (40-200μg/kg) was injected intravenously at the above noted light sleep patterns of EEGs generally changed into low voltage, fast activities in the neocortex and into regular slow waves of 3-5/sec. in the hippocampus in 40-90 sec. from the onset of Sch administration and these changes. lasted for 3-5 min. No appreciable change in blood pressure was observed in. association with these EEG arousal response. Such an EEG arousal response was also obtained even after the cerebellum. was removed.
3. The EEG arousal response was recognized neither in the case of intracarotid injection of Sch (10-40μg/kg) in cats immobilized with Flaxedil nor in the case of intravenous injection of Sch (40-200μg/kg) in encephale isole preparations.
4. On the basis of the above noted experimental results and of direct action of Sch to muscle spindles, the EEG arousal response following Sch administration may be attributable to the afferent discharges from muscle spindles.
5. It was supposed that such arousal effect of Sch was relatively weak in comparison with other procedures usually employed for eliciting EEG arousal response, because the response was not obtained with Sch injection (40-200μg/kg) in cats lightly anesthetized with Nembutal (2-5 mg/kg) in which distinct responses were observed by stimulation of the mesencephalic reticular formation or sciatic nerve.

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1. By means of reflexion photoelectric plethysmograph (RPPG), vascular activities of various areas of the human body surface were observed in relation to various external and internal environmental conditions.
2. Changes in various environmental conditions, namely, from high to low environmental temperature, from summer to winter, from a strained mental state to a relaxed one, etc., gave rise to parallel changes in RPPG patterns. Vascular activity could be classified into four types from view of changes in RPPG pattern of the thumb.
3. Vascular activities of various areas of the human body surface were similar to each other in certain conditions but were not in other conditions.
4. Vascular activity in an imbalanced state of the autonomic nervous system was studied by means of Mecholyl test and CO₂ inhalation test, and relationship between pattern-changes of RPPG and the activity level of the central autonomic nervous system was discussed.

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1. A peculiar phase other than p. p can be seen in human natural sleep, . which might be called reverse paradoxical phase (r. p. p), for the relation between EEG pattern and the activity level of many other physiological. functions is the reverse of that in p. p.
2. P. p and r. p. p are two different manifestations of the dissociation between EEG and many other physiological activities, especially vegetative functions.
3. The fact that p. p is apt to appear at the end of each single sleep cycleand r. p. p comes at the beginning or in the middle of each single sleep cycle could account for the phasic shift of changes in EEG and other physiological functions.
4. The prominent occurrence of p. p in the latter half and r. p. p in the first half of the natural night sleep could be attributed to the difference in distribution pattern of activity level of each physiological function. For instance, more occurence of EEG III can be seen in the earlier period of the night sleep, while the depressed or minor activity of GSR, blood pressure is distributed more in the latter half of the night sleep.

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The mechanical properties of frog muscles, especially the elasticity in addition to the viscosity and plasticity, were investigated.
1. The load-extension curve has two phases; namely, the first exponential phase for the lighter loads and the second linear phase obeying Hooke's law for the heavier loads. Under non-physiological conditions, the linearity of the curve tended to increase in most muscles.
2. For the temperature change ranging from 5°C to 40°C, the slopes of the second phase in load-extension curves were not affected in most cases.
3. Modified Young's modulus E was calculated, using sartorius (S), hyoglossus (H), ventricle (V) and oesophagus (O) muscles. The order of the arithmetic means of moduli was as follows: S>H>O>V. Usually the values ranged from 10⁵ to 10⁷ dyne per cm². When the logarithm of E was taken on the abscissa, the histogram of 88 preparations showed approximately a normal distribution.
4. Based on the calculation of a damped oscillation after quick release, the values of the viscosity coefficient of muscles were obtained, which were the order of 10² (g/cm-sec).
5. Plasticity increases with the time and magnitude of the previous loading, but it is removed completely by electrical stimulation.

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Collateral inhibition in the goldfish Mauthner cell consists of three different types of inhibition, i. e., the electrical inhibition, postsynaptic inhibition acting on the soma, and the third type of inhibition. The last one acts on presynaptic elements and on the lateral dendrite. Effects of strychnine and procaine, administered intramuscularly, were selective among these different types of inhibition. Strychnine blocked postsynaptic inhibition acting on the soma as well as the third type of inhibition leaving the electrical inhibition little suppressed, while procaine selectively blocked the electrical inhibition and the postsynaptic inhibition acting on the soma sparing the third type of inhibition. Possible mechanisms as well as loci of action of two drugs were discussed based upon these findings.

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In chronically denervated sartorius muscles of frog, the mechanical responses to direct electrical stimulations, caffeine-induced contracture, and the duration of plateau of the active state have been studied. The ATP-induced contraction of glycerol-extracted muscle fibers, which were prepared from denervated and contralateral innervated muscles, have been also observed.
1. The mechanical responses to direct electrical stimulations were gradually decreased with the lapse of time after denervation.
2. Even at the end of 30 days after denervation the resting and the action potentials of denervated muscle fibers were normal.
3. The developed tension due to 2 mM ATP in glycerol-extracted muscle fibers prepared from the 7 weeks-denervated muscles was not different from that in contralateral innervated muscle fibers.
4. Both the shape and the size of caffeine-induced contracture in denervated muscles were the same as those in the contralateral innervated ones.
5. The duration of plateau of the active state in denervated muscles was ranged from 22.6 to 29.2 msec. at about 18°C. These results were not different from those of the contralateral innervated ones.
6. Based on the above-mentioned results it is concluded that the E-C coupling process of frog sartorius muscle is depressed due to denervation.

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1. Experiments were carried out on 12 dogs (5-8 kg body weight) and 4 monkeys (2.3-3.2 kg) under chloralose anesthesia, and on 14 normal human subjects, in order to extend knowledge of the spino-bulbo-spinal (SBS) reflex.
2. In dogs and monkeys, stimulation of the spinal dorsal root yielded two types of reflex responses in the ventral root of the same segment. One of which was well-known mono- and poly-synaptic reflex responses with relatively short latencies and the other was a delayed reflex response with long latency.
3. The delayed reflex responses at the L₇ level in dogs and at the L₅ level in monkeys were respectively 30-35 msec. and 30-35 msec. in latency, 10-20 msec. and 10-20 msec. in duration, and 30-60μV and 40-90μV in amplitude.
4. When stimulus was applied to the afferent nerve in the hindlimb, two contrasting latency patterns were observed from spinal motor nerves at different segments, lumbar, thoracic and cervical. One of which was propriospinal reflex, the latency being increased as the recording points ascend the cord. The other was delayed reflex which decreased in latency as the recording points ascend the cord.
5. The delayed reflex response was evoked mainly with cutaneous nerve stimulation, and it was obtained only from nerves innervating flexor muscles.
6. When decerebration was made at the intercollicular level, the delayed reflex response was decreased in amplitude. In contrast, spinal transection at the C₁ level eliminated it completely.
7. Asphyxia and Nembutal anesthesia affected the delayed reflex response intensively and eliminated them much easier than the segmental polysynaptic reflex.
8. Averaged values determined in 3 dogs and 3 monkeys indicate effective spinal transmission velocities of 60±6 m/sec. in dogs and 61±6 m/sec. in monkeys for the ascending projections underlying the delayed reflex response, and 30±4 m/sec. in dogs and 28±4 m/sec. in monkeys for the descending projection of the delayed reflex response.
The above noted characteristics of the delayed reflex response in dogs and monkeys are almost the same as those of the SBS reflex response obtained in cats (SHIMAMURA & LIVINGSTON 1963). Therefore, it is reasonable to suppose that such a delayed reflex response may be the SBS reflex response in dogs and monkeys, although detailed analysis of the localization of the reflex center in the medulla oblongata has not been made in the present experiments.
9. In man, stimulation of the tibial nerve yielded a delayed reflex response with a latency of 70-80 msec. in the tibialis anterior muscle especially under light voluntary contraction of the muscle. This delayed reflex response was supposed to be due to the mechanisms of spino-bulbo-spinal reflex in man, judging from the fact that theoretically calculated latencies were coincident with those obtained in the present experiment.

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1. The effect of temperature on the mechanical properties and the action potential of isolated frog ventricle were studied.
2. On cooling to between 25°C and 8°C, the maximal tension and the contraction time increased while the maximal rate of rise of tension decreased, and the values of Q₁₀ were 1/1.82, 1/2.32 and 1.26 respectively. The maximal rate of proportional rise of tension, i. e. the ratio of the maximal rate of rise of tension devided by the maximal tension, decreased on cooling, and Q₁₀ of it was equal to the reciprocal Q₁₀ of the contraction time.
3. The force-velocity curve was hyperbolic at 8°C, but rather linear at 23°C.
4. Not only the duration but also the intensity of the active state increased on cooling, and Q₁₀ of them were about 1/2.6 and 1/1.5 respectively.
5. The work performed depended on the initial length of the muscle, the load and the temperature. Under the condition that the muscle was encounted by inertia force, however, more work than expected from above three factors was performed, accompanying the slowing of contraction.
6. Q₁₀ of the duration of action potential was 1/1.52, this is quite different from Q₁₀ of the contraction time or the duration of the active state.
7. The relation between the active state and calcium movement, and the energy mobilizing mechanism in cardiac muscle were discussed.

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