In the measurement of the pulmonary diffusing capacity D_L by the single breath method the entire inspiration time has hitherto been included in the breath holding time. When the inspiration time is prolonged, this treatment leads to a considerable error in the D_L value. In order to eliminate this error a correction factor of the inspiration time was newly introduced to obtain the effective inspiration time. The correction factor was a function of the ratio of the residual capacity to the total alveolar gas volume and the ratio of D_L to the flow rate of inspiration. A nomogram was made for convenience to obtain the effective inspiration time.

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The effects of various external media on changes in the transmembrane action potential of the rabbit atrium during repetitive stimulation after a long period of rest were studied.
1) The action potential elicited after the rest was characterized by a spike potential followed by a low-level plateau. Subsequent repetitive stimulation caused a progressive slowing down of the repolarization, an enhancement of the plateau and an increase in the amplitude of the action potential.
2) Sodium lack and TTX added solutions caused a considerable decrease in the initial rapid rise of a train of action potentials with little modification of the plateau. A gradual prolongation and an increase in the amplitude of the plateau during the repetitive stimulation were also observed with these solutions.
3) ACh abolished the plateau phase of the action potential without any modification of the initial spike potential, and suppressed changes in the action potential by repetitive stimulation remarkably. On the other hand, the plateau and the changes that were caused by repetitive stimulation were enhanced by the application of TEA.
4) Calcium-free and calcium-rich solutions had little effect on the first action potential after the rest. In the subsequent action potentials, however, some shortening of the plateau was caused in both solutions.
5) From the results, it was suggested that changes in the action potential by the repetitive stimulation could be explained by a decrease in the potassium conductance of the membrane in the sequence of stimulation.

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1. Single microelectrodes filled with solutions containing various anions were inserted into toad spinal motoneurons and used for both the electrophoretic injection of anions and for intracellular recording.
2. Judging from the effect of anion injections on the IPSP's, the activated inhibitory subsynaptic membrane was found to be permeable to Br^-, I^-, Cl^-, No₂^-, NO₃^-, N₃^-, ClO₄^-, SCN^-, OCN^-, ClO₃^-, and HCO₂^- ions. 3. BrO₃^-, F^-, HSO₃^-, HCO₃^-, CH₃CO₂^-, SO₄^2-, H₂PO₄^-, HPO₄^2- and citrate ions were found to be impermeable through the activated inhibitory subsynaptic membrane. The ineffectiveness of injection of HS^- ions on the IPSP was confirmed.
4. The time constants of the IPSP recovery after injections were evaluated for nine penetrating anions. Then a sequence was determined for the order of their relative ability to penetrate the motoneuron membrane: It is Br^->OCN^->NO₃^->NO₂^->SCN^->Cl^->HCO₂^->I^-> ClO₃^-.
5. Results obtained in the present investigation were compared with those from studies on cat spinal motoneurons and goldfish Mauthner cells.

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The membrane properties of the longitudinal smooth muscle of guinea-pig rectum and nervous factors influencing them were studied by the microelectrode technique using partition and field stimulating methods.
1. The membrane potential was 51mV, the maximum rate of rise of a spike was 9.4V/sec. The spike could be recorded in a Na-free (tris) solution.
2. Displacement of the membrane in a depolarized direction reduced the maximum rate of rise of a spike. A sigmoidal relation between the membrane potential and the maximum rate of rise of a spike was observed. Half value of the activation curve for a spike was-40mV.
3. When the membrane was hyperpolarized, the amplitude and the maximum rate of rise of a spike were reduced. However, in the presence of TEA (10^-3g/ml), reduction of the maximum rate of rise and the amplitude of a spike, due to hyperpolarization of the membrane, was prevented.
4. Field stimulation (0.5msec pulse duration) to the tissues evoked three different responses of the membrane, i. e. initial depolarization (EJP) with or without spike, hyperpolarization (IJP) and delayed depolarization, (delayed EJP) with or without spike. These responses appeared successively with different latencies.
5. The initial and delayed EJP were both postulated to be due to acetylcholine, released from the nerve terminals, acting on muscarinic receptors of the muscle membrane, since they were blocked by treatment with atropine (10^-7g/ml) and tetrodotoxin (10^-7g/ml). The IJP was blocked by treatment with tetrodotoxin and by cold storage (72hrs).
6. Prostigmine (10^-7g/ml) depolarized the muscle membrane and increasedthe frequency of spontaneous spike discharges. Field stimulation to the tissue in the presence of prostigmine enhanced the amplitude of the IJP. Hexamethonium (10^-7g/ml) reduced the amplitude of the IJP.
7. Generation of the IJP evoked by single (one sec or longer pulses) or repeated stimulation (0.5msec) modified the ionic conductance of the muscle membrane secondarily due to displacement of the membrane potential.

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The effects of isotonic Ca-Locke solution on the smooth muscle cell membrane of the guinea-pig taenia coli were investigated by the micro electrode and double sucrose gap methods.
1. In the Na-free Ca-Locke solution, the membrane was hyperpolarized from-42.5mV to-64.9mV and the input resistance of the membrane was increased. Spikes with overshoot potential could be evoked by electrical stimulation.
2. Treatment with tetraethylammonium (1mM) in the Ca-Locke solution depolarized the membrane (7mV), increased the amplitude of the overshoot potential from 17mV to 28mV, and decreased the maximum rate of rise of the spike from 19V/sec to 10V/sec.
3. In solutions containing isotonic Sr and Ba instead of Ca ions spikes could be evoked. However, in the Ba-Locke solution, the membrane was depolarized (about 20mV), the membrane resistance was increased and a plateau occurred during membrane activity. The Sr-Locke solution had effects on the membrane similar to those produced by the Ca-Locke solution.
4. The Mg and Co ions blocked spike generation in the Ca-Locke solution. However, the Mg ion did not suppress the spiking as greatly as the Co ion did. The affinity of the Co ion for the active site on the ionic gate is 6 times higher than that of the Ca ion and a 120 times higherthan that of the Mg ion.
5. The effects on the smooth muscle cell membrane of isotonic solutions containing divalent cations were discussed in relation to those on other excitable cell membranes.

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(1) Intracellular recordings were made in 41 neurons in the lateral geniculate nucleus (LGN) of cats anesthetized with Nembutal.
(2) The LGN neurons showed either the EPSP's fluctuating in two or three steps (37 neurons) or those with a large amplitude and an all-ornothing character (4 neurons). The time course and the amplitude of the EPSP's differed from unit to unit. The amplitude of the large EPSP's was near the firing threshold (3.1-11.5mV).
(3) The IPSP's recorded from the LGN neurons were classified into two groups: 1) short-term small IPSP's and 2) long-term large IPSP's. There were intermediate ones too. The small ones were 8-50msec in duration and 3-8mV in amplitude and the large ones, 50-170msec in duration and 6-22mV in amplitude.
(4) A sequence of the IPSP's occurred spontaneously and was elicited by electrical stimulation of the optic nerve (ON), visual cortex, superior colliculus and by light illumination of the retina.
(5) The LGN neurons were classified into three groups according to their first response to electrical stimulation of the ON. The Type 1 neuron responded with EPSP's to stimulation of one side of the ON. The Type 2 neuron responded with EPSP's to the stimulation of both sides of the ON. The Type 3 neuron responded with an EPSP to the stimulation of one side of the ON, and with an IPSP to the stimulation of the other side. Among a total of 12 units, 4 belonged to Type 1, 2 to Type 2, and 6 to Type 3. The latency of the IPSP's produced by stimulation of the dominant and nondominant ON's ranged 2.7-5.0msec and 2.5-6.0msec, respectively.
(6) By stimulation of the ipsilateral visual cortex, the antidromic spike discharge and an IPSP (latency 1.8-7.0msec) were elicited. Stimulation of Area 18 sometimes produced IPSP's.
(7) In the on-response neuron, the response to diffuse light illumination consisted of a high frequency burst of 3-4 spikes followed by an IPSP and then by spike discharges maintained during the light- “on.” A. recurrence of the IPSP's occurred during the light- “off.” In the offresponse neuron, the IPSP was induced by light- “on, ” and a succession of burst responses and the IPSP by light- “off.”
(8) The networks for the functionally reciprocal (the on-response and the off-response fibers) and also the networks for the inhibitory binocular interactions were discussed.

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(1) In twenty-two adult cats, septum after-discharges were induced, following placement of lesions in the hippocampus, amygdala and temporal cortex. The duration and frequency patterns of the after-discharge were analyzed.
(2) The hippocampus, in contrast to the amygdala, is the main contributor to the duration of the septum after-discharge. Septum discharge durations are shortest following massive hippocampal ablation. Increased seizure duration occurs at a much faster rate with an intact hippocampus and lesioned amygdala.
(3) The dorsal hippocampus is the predominant contributor of the faster frequencies in septum after-discharge patterns, whereas the ventral hippocampus and amygdala contribute slower frequencies predominantly.
(4) Septum after-discharges were longest following cortical resection alone. This suggested the existence of a cortical inhibitory effect upon limbic system after-discharges.

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1. The electrical activity and biophysical properties of the gall bladder and bile duct of the guinea-pig were investigated with microelectrodes. In addition, the relationship between the activity of the bile duct and that of the duodenum was observed.
2. In the gall bladder the mean resting potential was -36.9mV and there was usually no activity in Krebs solution. Ba⁺⁺, Ach or TEA depolarized the membrane (to 27.4mV in 2.5mm TEA) and initiated a spike discharge in bursts. The spikes had overshoots and plateaus on the falling phase. The time course of the foot of the spike was about 45msec.
3. Simultaneous records from 2 cells showed good synchronization of spikes which normally occurred first at the bile duct end. The conduction velocity measured from the interval between spontaneous spikes recorded from 2cells or from the latency after electrical stimulation was 4.2-8.5mm/sec.
4. The mean resting potential of the ampulla region of the bile duct was 51.3mV and of the rest of the bile duct was 38.6mV. Spontaneous bursts of spikes some with overshoots, occurred in the Krebs solution. The time course of the foot of the spike was about 11msec.
5. Synchronization of bursts but not individual spikes occurred. The conduction velocity of evoked or spontaneous spikes was usually 23-27mm/sec, but a wide scatter of values was obtained.
6. No electrical activity could be recorded from the hepatic ducts or from the cystic and bile ducts close to the hepatic ducts.
7. When the electrical activities of the ampulla and of the duodenum 1mm away were recorded simultaneously, no synchronization was observed between the two regions.
8. For both the gall bladder and bile duct the length constant (λ) was 0.7-0.8mm. The time constant of the membrane (T_m) was less than 100msec but could not be measured accurately.

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Effects of tetrodotoxin on the spindle potential and the spike of isolated frog muscle spindle recorded using the paraffin gap method were studied.
2×10^-8g/ml toxin first abolished the conductive spike and subsequently reduced the amplitude and the rate of rise of the abortive spike or the prepotential. 5×10^-8g/ml or more toxin erased the abortive spike and the prepotential without producing any significant effect on the spindle potential.
It is assumed from the results that the prepotential may be the same as the abortive spike, and that the abortive spike may play a primary role in the initiation of the conductive spike as the prepotential when its amplitude is higher than a trigger level.
The spindle potential was modified greatly depending on the sideward displacement of the axon in the paraffin pool during muscle stretch. Consequently, it seems that a part of the spindle potential may consist of an artifact.

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