1. In Ringer's solution in which Na was replaced with Tris-(hydroxymethyl)-aminomethane (abbreviated as Tris), the electrical properties of the sartorius muscle fiber of a frog (Rana nigromaculata nigromaculata) was investigated.
2. In Tris-Cl Ringer's solution, the effective membrane resistance was decreased at the depolarization and increased at the hyperpolarization, while in Tris-SO₄ Ringer's solution it was increased at the depolarization and decreased at the hyperpolarization. It might be due to the change of the Cl conductance at the strong polarization. The Cl conductance was also changed with time and it seemed to be one of the reasons to produce the delayed rectification.
3. In Tris-SO₄ Ringer's solution, the same graded slow response as that in Cl-free solution with normal Na concentration was observed after termination of the strong anodal pulse. Na is not considered to have an essential effect on the response in Cl-free solution. The same result was also obtained in K-rich solution. The slow break response appeared as a negative potential component in low K solution, while it did as a positive potential component in K-rich solution. In the former, the effective membrane resistance was decreased during the production of the response, while in the latter it was increased. It might be explained mainly by the change of the K conductance.

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1. In the sartorius muscle of the frog, the structure and function of the extrafusal receptors were compared with those of the spindle receptors.
2. There were 5-7 spindle receptors and 10 or more extrafusal ones in a sartorius muscle.
3. The structure of the spindle receptors in the sartorius muscle conformed. well with that observed in the small toe muscles by many workers, except that, in the living preparation, myelinated subbranches of the parent axon. within the spindle capsule assumed an appearance of chains of ball-like swellings. There was observed some seasonal variation in the size of these swellings.
4. The parent axons supplying the spindle receptors ranged from 7 to 18μ in diameter, and the conduction velocity of the impulse travelling along them from 11.4 to 29.7m/sec.
5. The spindle receptors were stimulated by stretching the muscle at a constant velocity and from the frequency-extension curves their static sensitivityto stretch was calculated as 12 impulses/sec/mm on the average. They generated impulses in response to abrupt focal deformation produced by the displacement of a glass rod. The mean threshold value to the displacement was, 17μ.
6. In the proximity of the endings, the parent axon of the extrafusal receptors usually divides into two or three branches at every node and finally they form leaf-like expansions of unmyelinated threads, and accordingly its receptive field spreads over the surface of several or more muscle fibres.
7. The parent axons of the extrafusal receptors were 3 to 11μ in diameter, and the conduction velocity of the impulse carried along them was between 10.2 and 20.0m/sec.
8. The extrafusal receptors were distinguished from the motor end-plates for the following reasons:(i) Impulse discharges set up from the former inflow exclusively into the dorsal root;(ii) no miniature endplate potentials aredetected when a microelectrode is inserted into the muscle fibre in immediate juxtaposition to the former.
9. The extrafusal receptors could be classified into two groups; one having threshold at extension of the muscle by 110% of the resting length in situ and another by 140%. The static sensitivity of the former was calculated as T impulses/sec/mm and that of the latter no less than the former. As for the: threshold to focal displacement, there was virtually no difference between them, the mean value being 52μ.
10. The functional significance of afferent discharges from the extrafusal receptor was discussed in comparison with those of group Ib and group III muscle afferent.

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In order to analyse the function of the pyramidal tract, studies were made on the effects of pyramid stimulation upon flexor and extensor motoneurones and also upon gamma motoneurones innervating the hindlimb of cats.
Special care was taken to eliminate all the possible indirect effects of pyramid stimulation upon the above noted neurones due to current spread to the structure in the medulla, through collaterals of pyramidal fibers to the structure of the brain. stem and also through the gamma-loop at the spinal segmental level. For this purpose, medullar and pontine structures except the pyramidal tract was entirely removed by means of electrocoagulation and suction, and the pyramidal tract was transected at the midpontine level. All ventral roots from L4 downwards were cut bilaterally or unilaterally.
1. Effective points of stimulation upon spinal motoneurones were found to be distributed in the contralateral, vertical plane in the pyramid 1.0 mm lateral from the midline. However, those upon gamma motoneurones were dispersed rather diffusely in the pyramid.
2. With repetitive stimulation of the pyramid monosynaptic and polysynaptic reflex discharges from flexor motoneurones increased in amplitude in all 16 tested cases, whereas those from extensor ones showed appreciable decrease in amplitude in 12 out of 16 tested cases.
3. Following single pulse conditioning stimulation of the pyramid, increase in amplitude of the flexor monosynaptic reflex discharge was observed for 30-40 msec in all 10 tested cases. Whereas, monophasic decrease in amplitude for about 30 msec and inhibitory effect for about 30 msec with initial slight facilitatory one were recognized respectively in 14 and 3 of 17 tested cases of extensor motoneurones.
4. As to the effect of pyramid stimulation upon individual motoneurones, facilitatory effect was obtained in the case of flexor motoneurones, whereas inhibitory one was observed frequently in the case of extensor ones judging from the firing index method.
On the other hand, EPSPs were evoked in 12 flexor and 6 extensor motoneurones, IPSPs were evoked in 8 extensor ones and mixed form of EPSP and IPSP were observed in 2 extensor motoneurones.
5. These results provide basis for the suggestion that the pyramidal tract as a whole has a stronger facilitatory control over flexor motoneurones than over extensor ones and that these facilitatory pyramidal fibers to flexor motoneurones may exert a certain inhibitory effect upon extensor motoneurones.
6. Facilitatory effect upon gamma neurones: increase in frequency of spontaneous discharges or initiation of discharges, as well as inhibitory effect: decrease in frequency of spontaneous discharges, were observed respectively in 4 and 10 out of 30 tested cases with pyramid stimulation.

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The authors have constructed a micro-glass pH electrodes of the size about 60 to 80 micra in diameter and 4 to 9mm long and the electrode characteristics and applicabilities to the intracellular pH measurements were studied.
1. Paired with a KCl-filled micropipette leading to a reference electrode, the micro-glass pH electrode was confirmed to give an electromotive force per pH unit which closely satisfied the theoretical requirement of Nernst equation.
2. Tested for a standard buffer of known pH, this micro-glass pH electrode gave pH readings as reproducible as did a large glass pH electrode; thus the standard deviation of mean of ten consecutive measurements was 0.005 pH for both electrodes.
3. This micro-glass pH electrode was applied to the intracellular pH measurement of the sap of a single cell of Nitella flexilis, a fresh water alga. Stable intracellular pH recordings were obtained with minute fluctuations less than 2 mV (0.04 pH) for the period of at least 30 minutes, during which a normal plasma streaming continued around the electrode and up to the very edge of the cut end. The mean pH of the sap was 5.6 at 20°C for a lot obtained from pond in November, in a good agreement with a previous measurement by IRWIN (1923, 1930). From two consecutive measurements in one and the same cell, it was concluded that a single pH measurement in Nitella gave a pH reading which was reproducible with errors of less than 0.1 pH.

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1. Effects of stimulating upper brain centers upon lumbar spinal alpha motoneurons, especially extensor ones, were analysed with intracellular potential recordings. Recordings from single spinal interneurons and descending tract fibers were also attempted in combination with upper brain stimulations.
2. Single stimulations of the bulbar reticular formation and the fastigial and the dentate nucleus elicited usually two group facilitations upon extensor motoneurons in population, the early and the late group facilitations. The early depolarizing PSP's, corresponding to the early group facilitation, were elicited by the stimulation markedly in phasic motoneurons but scarcely in tonic motoneurons. The late depolarizing PSP's, corresponding to the late group facilitation, were set up prominently in the tonic motoneurons but undistinguishably in the phasic motoneurons. Differences between PSP's of the phasic and the tonic motoneurons were observed also with the stimulation of the pyramidal decussation and the ventral-lateral nucleus of the thalamus. Such differences were rather quantitative and clear only in the extreme cases. Many extensor motoneurons responded to the stimulations in intermediate manner.
3. Response manners of spinal interneurons and descending tract fibers to the upper brain stimulations were, in approximation, classified into three, being the two specific types of PD and RF and the unspecific type. These interneurons and descending tract fibers may modulate and mediate supraspinal influences upon alpha motoneurons differentially and respectively.

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1. The response of the chorda tympani nerve of cats to stimulation of the tongue by NaCl, quinine, HCl, water, saccharine and Ringer's solution was recorded.
2. The magnitude of the integrated response, produced by stimulation of the tongue with Ringer's solution, is increased by increasing or decreasing the temperature of solutions from 30°C, indicating that the nerve conveys impulses to the warming and cooling of the tongue.
3. When NaCl, quinine or HCl solutions of varying concentrations and temperatures were applied to the tongue, the increase in the response magnitude with an increase in the concentration became smaller as the temperature was deviated from 30°C, and the response to taste stimuli alone was found to be greatest at 30°C.
4. Afferent impulses in single chorda tympani nerve fibres were recorded and it was found that nearly all of the units, sensitive to taste, also responded to thermal stimuli.
5. In single units the greatest increase in the impulse frequency with an increase in the concentration of taste stimuli was obtained at 30°C and the impulse frequency did not change appreciably with a change in concentration at 5°, 10° or 45°C.
6. The results indicate that the taste sensitivity to NaCl, quinine and HCl is greatest at 30°C, or at the temperature of the tongue.

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Binding and inactivation of Pitressin by serum and plasma in vitro were studied. The pressor activity of Pitressin added to human serum was usually lower than that of Pitressin dissolved in saline of the same concentration. Plasma did not reduce the activity under the experimental condition used. The reduction of activity seemed to be due to inactivation of the hormone progressing during a period of assay, not by binding of the hormone by serum protein. Rat serum samples tested did not affect the activity, while dog serum reduced it. The Pitressin binding capacity of serum, measured by dialysis technique, was approximately same as that of plasma. Both Pitressin binding and inactivating capacities differed from one human serum to another.
Human sera with larger binding capacity inactivated Pitressin to larger extent, and a significant correlation existed between these two capacities.
COHN fractions II+III and sometimes IV-4 attributed to both Pitressin binding and inactivation. A correlation between these capacities was also found in COHN fractions.

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The effect of oxytocin upon the hippocampal EEG has been studied in unanesthetized cats prepared with acute lesions in the rostral brain stem or in the posterior basal diencephalon.
The results are as follows.
1. Following intracarotid injection of 0.1-0.3 u. of oxytocin, the alteration of the hippocampal EEG was characterized by the hippocampal hyper-arousal waves with the latency of 20-40 seconds, lasting 30-90 seconds both in the intact cat and the adrenalectomized cat. The appearance of this response is intermittent rather than continuous.
2. Following intravenous injection of 0.1-0.5 u. of oxytocin, the unit discharge in the rostral midbrain reticular formation increased with the latency of 30-60 seconds and with sustained firing for 1-2 minutes. The highest rates observed, were about 20-30 cycles per second.
3. Regarding lesions in the posterior midbrain tegmentum, perisqueductal grey, rostral midbrain tegmentum and posterior basal diencephalon, only the latter could block the appearance of this response elicited by the administration of oxytocin.
4. Lesions in the lateral hypothalamus, the subthalamic region, or the septal region, which constitute a nodal area in the afferent pathway to the hippocampus, also block the appearance of this response.
5. Intracarotid injection of 0.3-0.5 u. of vasopressin-like substance could introduce this response in 7 out of 11 cats with the acute rostral midbrain tegmental lesion.
These results offer evidence in favor of the existence of an oxytocin-sensitive component within the midbrain reticular activating system, including the posterior hypothalamus and the adjacent region; also, the afferent discharge, from the oxytocin sensitive component in the midbrain activating system in response to circulating increased oxytocin, activates the hippocampus via the lateral hypothalamus and the septum.
6. Authors discussed oxytocin-sensitive component in the reticular activating system from the biological viewpoint of homeostasis.
These results were partly reported at the second Reproduction Symposium of the Japan Endocrine Society, in March 1962 and at the 39th General Meeting of the Physiological Society of Japan, in July 1962.

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