1. Facilitation of nerve muscle transmission by repetitive stimulation was usually observed in frog preparation with wide range of stimuli frequencies, while occasionally observed in rat and rabbit muscle in situ only at certain range of frequencies. The facilitation of frog muscle was made more remarkable by reducing Ca concentration in the medium, and was made less remarkable by post-tetanic potentiation and Ca increase in the medium.
2. Double shock experiment on frog preparation showed two distinguished kinds and an intermediate of the spike height-interval curve. One curve should be transfered to another by changing the Ca concentration in bathing medium.
3. Double shock experiment on single nerve fibre-single muscle fibre preparation showed that there were two modes of transmission; in one, the impulse was transmitted by the first as well as the second shock, but the second shock occasionally failed in some definite shock interval. In the other, the impulse was transmitted only by the second shock, and that only in some limited phase of shock intervals. And the one could be transfered to the other by changing the Ca concentration.
4. The various spike-interval relation observed in the whole muscle could be explained by considering the relative composition of these two kinds of synapses.
5. The time course of the size of the second e. p.p. did not show two kinds, but the difference of whether it attains the firing level or not would give rise to two kinds of synapse.
6. Repetitive stimulation was carried out also on the frog end-plate potential, small nerve junctional potential and the fish muscle, showing facilitation in a certain range of frequencies.
This research was supported in part by a research grant from the Educational Ministry.

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1. In the strychninized olfactory bulb of curarized rabbits, single shock stimulation of the olfactory epithelium was found to bring about a monophasic negative wave of 20-40msec. duration (N-potential) followed by a train of 30-50 cps oscillatory wave lasting 200-400msec.(R-wave). The properties of the R-wave were studied in comparison with the induced wave and the N-potential.
2. The R-wave and the induced wave readily disappeared after intravenous injection of pentobarbital sodium. The N-potential was more resistant than the R-wave or the induced wave.
3. During asphyxia, the R-wave was lost simultaneously with the induced wave.
4. The R-wave disappeared during anterior commissure stimulation and augmented in the post-stimulation period, just as did the induced wave.
5. By high frequency stimulation in the mesencephalic reticular formation, the R-wave was markedly suppressed.
6. The R-wave had a much longer recovery cycle than that of the N-potential.
7. The R-wave reversed in polarity in a deep layer of the olfactory bulb. The reversal point was slightly deeper than that of the N-potential.
8. A number of units in the olfactory bulb discharged rhythmically bearing a clear phase relationship with the R-wave. In some units, suppression of the spontaneous discharge was observed during the excursion of the R-wave.
9. From these findings, it was inferred that the R-wave had a generating mechanism in common with the induced wave. The origin of the R-wave was discussed in connection with that of the N-potential. The authors are grateful to Dr. Kitsuya IWAMA for his invaluable discussion throughout the course of this experiment. A part of the expense for this work was defrayed by a grant of the Ministry of Education.

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The function of the vagal and splanchnic afferent system of the stomach was compared by recording afferent impulse discharge from nerve trunks or single nerve fibers during mechanical stimulation of the stomach of the toad. The results are summarized as follows:
1. The receptive fields of single vagal afferent fibers were far smaller than those of splanchnic fibers. The former was localized in the cardiac portion and the latter along the lesser curvature.
2. There were three groups of the nerve fibers in reference to their diameters. Vagal afferent fibers belong to the medium group and splanchnic fibers belong to small or large diameter groups.
3. The adaptation of vagal mechano-receptors was rapid and that of splanchnic mechano-receptors was relatively slow in general.
4. The vagal receptors were excited by passive distension and active contraction of the stomach. The splanchnic receptors responded only to extreme distension of the stomach wall and traction of stomach mesentery.
5. It was found that vagal gastric mechano-receptors are situated in the mucosa or submucosa of the gastric wall and splanchnic mechano-receptors are in the serosa or subserosa.
It is concluded that the function of vagal afferent fibers from gastric mechano-receptors is to signal the mechanical deviation of the gastric wall related to fullness or hunger sensations and that of splanchnic receptors is to signal pain or other sensation.

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1. Pontine and bulbar reticular formation (RF) and Deiters' nucleus were stimulated stereotaxically with brief electric stimuli (2-3msec.) and their effects. on the intracellular potential of lumbar alpha motoneurons as wall as on the size of monosynaptic reflex were studied in the cat. Secondary effects through. the gamma efferents-muscle spindle loop were eliminated.
2. Stimulation of pontine RF, especially its rostral part, produced a marked inhibition of extensor monosynaptic reflex at a latency of 15-20msec. and a slight facilitation of flexor monosynaptic reflex at a latency of about 10msec.
3. Stimulation of Deiters' nucleus was facilitatory to extensor monosynaptic reflex. The facilitation appeared in two separate phases, the one set up at a latency of less than 10msec. with relatively short and simple time course and the other at a latency of 15-20msec. with a longer duration.
4. The effect of stimulation of the bulbar RF varied extensively with a, slight change in the electrode position. The most prevalent effect was facilitatory to extensor monosynaptic reflex, which in some cases resembled that of Deiters' nucleus in its time course.
5. Generally speaking, changes by stimulation of intracellular potential of spinal motoneurons reflected the influences elicitable from the same site upon the size of monosynaptic reflex. Facilitatory or inhibitory influence upon the reflex size could mostly be accounted for by the potential change of the motoneuron membrane which was most likely due to EPSP's and IPSP's.
6. Single spinal motoneurons fired from different levels of depolarization, when the rate of rise of depolarizing PSP's was different according to the stimulated site in the brain stem.
7. The effect of repetitive stimulation of the RF on the membrane potential. of single spinal motoneurons could be illustrated in general as a summated. effect of single stimulation of the same site.
8. Tonic suprasegmental influences and their modification by reticular stimulation were visualized as maintained discharges of descending tract fibers and. spinal interneurons.
9. A hypothetical accout for the decerebrate rigidity was put forward based on the present findings.

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1. Rabbit's brain and spinal cord were homogenated in 0.32M sucrose and fractionated into six subcellular fractions (nuclear, mitochondrial, vesicular, amorphous, microsomal and cytoplasmic) by applying WHITTAKER'S fractional centrifugation in a density gradient, and the activity of substance P in these subcellular fraction was compared.
2. A greater part of SP activity (about 50-70%) was found in the vesicular and cytoplasmic supernatant. So the neuronal SP activity would be chiefly of particulate origin.
3. Such particulate SP was released not so easily by treating with 0.32M sucrose at neutral pH in the cold. But it was liberated with relative rapidity by raising temperature (60-100°C), acidification (pH3-4) and hypotonicity.
4. On incubation with the microsomal fraction of neuronal tissues the particulate SP activity as well as extracted SP were inactivated, but other fractions showed hardly any inactivating effect. Such an inactivating power of the supernatant fraction was suppressed by adding strychnine or LSD-25 into the incubation media, while it was completely destroyed by boiling but not lost by dialysis. Hence this action would be of enzymic nature.
5. Electron-microscopical observations were also made on these subcellular fractions and it was confirmed that the vesicular fraction was chiefly composed of smaller particles of 200-3000Å in diameter, while the neuronal microsomes could be differentiated into two categories; solid and membrane-like ones. The microsomal SP and SP inactivating enzyme would be probably present in some particles in the latter.

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The effects of GABA and its derivatives on blood pressure, respiration and heart rate of the rabbit were investigated.
1. 4-Aminobutanol, N-methyl-4-aminobutanol and n-butyric acid had not any effect on blood pressure and respiration.
2. N-Methylation (N-methyl-GABA, N-dimethyl-GABA, N-trimethyl-GABA), Nphenylation and N-acetylation reduced profoundly the effects of GABA on blood pressure and respiration.
3. Esters of GABA had more or less apparent hypotensive effects on blood pressure.
4. GABA-methylester elicited a depressor response which was of the same order in magnitude, but extremely shorter in duration in comparison with that induced by GABA.
5. The depressant potency of GABA-methylester was not increased by N-monomethylation, but increased by 2-3-fold with N-dimethylation and by about 60-fold with N-trimethylation. The hypotensive effect of N-trimethyl-GABAmethylester was about 1/2 of that of ACh.
6. Other methylesters were compared for their hypotensive effects and placed the following descending order; N-methyl-GABA-methylester>N-butyl-GABAmethylester>N-phenyl-GABA-methylester>N-ethyl-GABA-methylester.
7. On the other hand, esters of N-methyl-GABA were placed in the following descending order methyl-GABA-methylester, methyl-GABA-benzylester>methyl-GABA-ethylester>methyl-GABA-butylester.
8. The above described derivatives usually did not produce any change in respiration.
9. Except of N-trimethyl-GABA-methylester, other methylesters did not elicit so appreciable bradycardia.
10.β-Hydroxy-GABA and its methylester had respectively a weaker hypotensive action than GABA and GABA-methylester.
11. Nicotinic acid and isonicotinic acid elicited rarely a depressor responce. Their methylesters had a stronger action than the acids, but a far weaker one than GABA-methylester or N-methyl-GABA-methylester.
12. The hypontensive action of methylesters of GABA was greatly reduced by atropinization. N-Trimethyl-GABA-methylester had a considerably strong nicotine action.
13. Intrathecally applied GABA elicited a much stronger and longer lasting depressor response than intravenously administered GABA. On the other hand, methylesters and N-substituents of GABA produced hardly a depressor response, when applied intrathecally.

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The investigation of the effect of anomalous anions on the caffeine contracture was made, with the following results.
1. The caffeine contracture occurs not only in normal Ringer's fluid but also in K-Ringer's, and in the latter it is rather enhanced.
2. The caffeine contracture is enhanced by anomalous anions in the following order regardless of the sorts of Ringer's, SCN>NO₃>Br>Cl.
3. The time course of the caffeine contracture is of double phase in the range of the intermediate concentrations of the drug, and this occurs regardless of the sorts of Ringer's and of whether the anomalous anions are present or not.

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