1. Using the single node of Ranvier, the effect of nitrate and thiocyanate ions with or without cobalt ion was studied.
2. The substitution of chloride ions by these less permeable anions resulted in decrease of the critical membrane potential for firing and decrease of the spike height.
3. The prolongation of the action potential by cobalt was enhanced in the nitrate or thiocyanate Ringer.
4. Chloride depletion is resistant to the inhibition of potassium depolarization by cobalt.
5. These results can be explained by the consideration that chloride permeability plays an important role in the node of Ranvier.
6. The prolongation of the action potential by cobalt application can be explained speculatively by supposing that the inactivation of sodium carrier system is inhibited by cobalt.
7. From the inhibition of potassium depolarization by cobalt, the selective inhibition of potassium permeability was concluded.

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A method is described for measuring the safety factor for transmission of excitation in mammalian cardiac muscle.Dog trabecular muscle fibers were used. Urethane and cocaine were applied to the perfused fibers and the progressive changes in threshold (T) and action potential (A) recorded.The ratio between these values in their normal (n) and depressed state (b) just as block occurs was used to determine the safety factor: An/Ab×Tb/Tn=Safety Factor. The values thus obtained in trabecular muscle were 1.5 to 3.5.When anelectrotonus and catelectrotonus were used vary thresholds and action potential amplitude, the factor of safety found was somewhat higher: 2 to 7. It is concluded that the factor of safety varies in the same tissue and that in certain anatomical situations it is much less than in large diameter parallel fibers.

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The susceptibility to endotoxin intoxication in rabbits was found to undergo a marked seasonal variation, being increased in winter and the least in summer. The activation of thyroid gland in winter was found to be related to the intense dyspneic response due to epinephrine discharge in this season. However, the characteristic metabolic derangements, such as the depletion of the liver glycogen especially pronounced in winter, was shown to be independent from it and seemed to be related to the enhanced hepatic metabolism in cold adaptation.Concerning the summer non-susceptibility, besides the lessening of the above potentiating factors, an assumption of some central alterations in reducing the disturbances in the autonomic nervous system in relation to the activation of the febrile mechanism seemed to be necessary.

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1. The dynamic visco-elastic properties of glycerol-extracted muscle were investigated.
2. The dynamic stiffness increases during contraction and decreases during relaxasion. The stiffness-tension relation is linear in most parts of either contraction or relaxation processes, and its tangent is almost equal to each other.
3. When the sinusoidal changes in length (peak to peak) are less than 1.5 per cent of muscle length, the fiber's obey HOOK's law.
4. The complex modulus measured at the frequencies of 20 or 40c/sec of contracted muscle is 7000 or 10000gwt·cm^-2. The modulus is decreased to 800 or 1200gwt·cm^-2 if the muscle is relaxed in 100 mM pyrophosphate-Na solution or 1 M KC1 solution, and to 2000gwt·cm^-2 in 50 mM pyroposphate-Na solution containing 2mM MgCl₂.
5. Elastic modulus and viscosity are calculated based on the rheological analysis. The retardation time is 0.8 or 2.0 msec.
6. When the muscle is stretched, the stiffness is always increased.
7. From the time course of decay of tension after quick stretch, it is suggested that there would be another system possessed of time constant of a few seconds than the system detected by sinusoidal analysis.
8. Visco-elastic properties and their changes in contraction process of glycerolextracted muscle are similar to those of living muscle.

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1. Glass micropipettes were inserted into the oculomotor nucleus of the cat and electrical activities and properties of the neurons were studied with intracellular recordings.
2. The properties of ocular motoneurons were, in many respects, alike to those of lumbar spinal motoneurons. However, when compared with the latters, several characteristics of ocular motoneurons were noted; rather smaller time constant, shorter duration of after-hyperpolarization, lack or scarcity of collateral inhibition, much more frequent rates of tonic and phasic discharges and so on.
3. The local reflex activity in the oculomotor system was scarcely observed, but a few cases were encountered that seemed to be alike to those of proprioceptive responses in the spinal motor system.
4. Synaptic potentials in ocular motoneurons due to the VIIIth nerve stimulations were visualized by the intracellular recording, and their relations with focal potentials in the oculomotor nucleus and with discharge outflows to the IIIrd nerve, elicited by the same stimulations, were examined in concern with the vestibulo-ocular reflex.

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By stimulating the lacrimal gland of rabbit with pilocarpine, the tears were collected through the fistula inserted into the nasolacrimal duct, and the ionic composition was analysed with special reference to the rate of lacrimal flow, and the ionic concentrations in serum. The secretion potential wasalso measured with reference to the secretion of ions in tears. Results obtained are as follows:
1. The osmolarity of tears is mainly produced by salts which are mainly composed of Na⁺ and Cl^-and partly of K⁺and HCO₃^-and is kept almost con stant at a slightly higher level than that of serum, irrespective of the rate of tear flow. The concentrations of Nat HCO₃^-and Cl^- in tears are all kept constant, irrespective of the rate of tear flow, while the K⁺concentration changes parallel to changes of the rate of tear flow.
2. The concentrations of Na⁺and HCO₃^- in tears are approximately the same as that of the respective ion in serum even when the concentration in serum is changed by salt infusion, while K⁺ and Cl^- concentrations are always higher in tears than in serum. The Cl^- concentration in tears bears a linear relation with that in serum of which the regression coefficient is 1 and the intercept constant is about 25mEq. The pH of tears is approximately the same as the serum pH and is determined by HCO₃^- concentration and CO₂ partial pressure which equilibrate with those in serum.
3. The potential being measured by external leading from the luminal side and the outside of the lacrimal gland, a resting potential of about 4-27mV was detected. The negative side of the potential is in the lumen of gland. The negativity of the potential in the luminal side increases as the rate of tear flow is increased by stimulation of lacrirnal gland, and thus the secretion potential of about 7-22mV appears. The secretion potential runs parallel to the time course of the rate of tear flow, though the peak of the former somewhat lags behind that of the latter.
4. The increase of the resting potential as well as the secretion potential was provoked by raising the Cl concentration in serum by NaCl infusion. The changes of potential may be due to the acceleration of secretion. On the other hand, the potential was reduced after KCl infusion, probably owing to the promotion of K⁺ secretion by a rise of serum K⁺ concentration.
5. From the above results and analysis of the interrelation between the rate of tear flow and the rate of ionic secretion as well as the secretion potential, it was deduced that the secretion potential as well as the water secretion (tear flow) of the lacrimal gland is associated with the active secretion of Cl^- through the lacrimal gland cells, while Nat HCO₃^- are all transported passively in equilibration with those in serum. The K⁺ secretion is also an active process and affects the secretion potential to decrease.

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The effects of 10^-5 and 10^-4gm/ml sodium 1-thyroxine on the bullfrog's slow muscle fibers innervated by the small motor nerve and on the neuromuscular transmission were investigated by means of the intracellular microelectrodes technique.
1. The slow muscle fibers were affected by more than 10^-4 thyroxine-Ringer solution. The resting potential was slightly hyperpolarized but insignificantly. The effective membrane resistance, however, considerably increased to three folds of that in the control solution. The neuromuscular transmission was facilitated, i. e. amplitudes of the s. j. p.'s were augmented by 180%. The s. j. c. under the voltage clamp condition was also augmented by 240%, while their durations somewhat decreased.
2. Ach-potentials produced by the ionophoretic microapplications of acetyl choline are remarkably increased by 10^-4 thyroxine.
3. From these evidences, it was concluded that thyroxine accelerated the neuromuscular transmission by both increasing the resting muscle membrane resistance and enhancing the sensitivity of the receptor membrane for the released transmitter substance from the nerve endings. It was also discussed that other factors such as the anticholinesterase-like action of thyroxine and an increase in the amount of the transmitter substance from the nerve endings were not conceivable.
4. The relationships between the thyroid hormones and the neuromuscular disorders in the cases of either the thyrotoxic or the familial form of periodic paralysis were discussed.

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