The maximum voluntary ventilation (MVV) has been measured up till now as the only index of the ventilatory dynamics under high atmospheric pressures, as the MVV is known to decrease with the increase of the density in accordance with the formula: MVV=1/√(density) (S. Miles). As referred in several reports, the said formula has been confirmed as valid to the MVV observed under hyperbaric environment. However, there still remain some problems to be solved in the measurement of the MVV itself, such as the breathing mechanics involved. It is uncertain that the MVV reflects clearly the ventilatory dynamics under high pressures. This paper shows some experimental studies to determine the best indicator which faithfully expresses the ventilatory dynamics under the hyperbaric environment. The pressure-flow relatioship of the air flow in a simulated breathing by a sine wave pump, satisafied under various ambient pressures is expressed by the Rohrer's equation: P=K₁V-K₂V² (P: driving pressure, V: air flow, and K₁ & K₂: parameters concerning the physical properties of the gas mixture), being a nonlinear relation. It was obvious that the parameter K₂, concerned with the gas density, increased proportionally to the increase of the depth. The K₂ value tended to increase with the increase of the turbulance in ventilation. The viscous resistance (viscance) value △P/V followed straight lines in respect to the increase of atmospheric pressure and the gradient became larger with the increase of the air flow. Viscance value nearly doubled at 4 Ata compared with those at 1 Ata. MVV in 14 subjects, having approximately the same ventilatory functions, decreased with the increase of the ambient perssure. The observed MVV under high perssures showed decreases by 40.3% and 53.4% at 4 and 6 Ata respectively against the MVV value at 1 Ata, and %MVV were 61.8% and 50.3% respectively, while their observed %MVV at 1 Ata were 105%. This means that the ventilatory dynamics capacity become in almost half of the 1 Ata values. The measured FEV_1.0 or one minute value of "vital capacity through effort" under increasing ambient pressures did not coinside with the predicted velues. And the decrease of the rate of FMF_25-75% or intermediate flow-rate through maximum effort at 1 to 6 Ata was very significant, i.e. 46.5% and 59.6% at 4 and 6 Ata respectively. As a result of this study, the following formula was obtained: Y=2.0689X-<0.4452> (Y: measured FMF, X: ambient pressure). The FMF values thus obtained could well represent the pressure-flow relationship of the air flow in the simulates breating under various ambient pressures. Accordingly, the FMF value reflects the ventilatory dynamics faithfully under hyperbaric environments. This fact depends on the "effort independent" during the measurement, because hyperbaric effects of the ventilation are only reflected in the increase of viscous resistance of the air-way. On the contrary, the MVV under hyperbaric environments is influenced by the respiratory muscles, elastance and inertance during one cycle of ventilation. consequently, at MVV measurement, certain errors may be introduced to the measured values. Therefore, mean decrease rate of the MVV does not agree with the calculated value from the Mile's formula, being smaller than those obtained by other authors, and FEV_1.0 values obtained at hyperbaric environments do not also reflect the hyperbaric effect.

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As a preliminary step to furnish date for determining the MAC value of acetone, some biological reactions were checked on subjects who under went "one-day exposure", i.e. exposures in the morning and afternoon for three hours each in a day, to acetone. Twenty-five healthy male students about 22 years old were selected as the subjects, being divided into 5 groups. Four groups were exposed to 1000, 500, 250 and 100 ppm acetone respectively for 6 hours with 45 minutes' intermission in the middle, the remaining group being the control. Responses of the subjects to acetone were observed for 56 hours after the beginning of the exposure. 1) Subjective symptoms Odor of acetone was more or less recognized by all the exposed groups, but while the exposure lasted the subjects seemed to get used to the sense of smell. Irritation on the mucous membranes was recognized by most of the 1000 and 500 ppm groups, but only a few recognized it in other groups. The organs on which the subjects recognized irritation most were nose, and then eyes, throat and trachea in the decreasing order. Chiefly in the 1000 and 500 ppm groups, some complaints of a physical disorder were noted in the following morning. These complaints were a feeling of tentin, general weakness, heavy eyes, lacking in energy, etc. In the 250 ppm group persons corresponding to about half the complainants in the 500 ppm group in number complained the above symproms, whereas almost none in the 100 ppm group made a complaint. 2) Acetone concentration in the blood and urine In the 1000, 500 and 250 ppm groups, acetone concentration in the blood had obviously increased since the beginning of the exposure, and it reached the maximum value in 7 hours, i.e. 15 minutes after the exposure was completed. It decreased to the ordinary value in 48 hours, i.e. in the morning after next, in the 1000 ppm group, in 32 hours in the 500 ppm, and 24 hours in the 250 ppm. There is a certain correlation between the acetone concentration in the blood and that in the air in each group, but not a direct proportion. Almost the same changes were noted in acetone concentration in the urine. 3) Behavior of leucocytes Leucocyte counts of the peripheral circulating blood increased after the beginning of the exposure more than the daily fluctuation in the 1000 and 500 ppm groups, but in the other groups they did not so much. In the classification of leucocytes no distinctive signs were noted even in the two former groups. Circulating eosinophil counts increased in the 1000 and 500 ppm groups in contrast with the daily fluctuations of the other two exposure groups and the control. They decreased to the ordinary value in 32 hours. Phagocytic activity of neutrophils reduced after the beginning of the exposure in the 1000 and 500 ppm groups, recovering to the previous value in 48 hours. A slight decline of phagocytic activity was observed in the 250 ppm group, but not in the 100 ppm group. 4) Other findings in the urine Some abnormal signs were found in the reaction of urobilinogen in the urine in the 1000 ppm group, but not in the other groups. The findings were obtained in the evenings of the day of the exposure, i.e. 7 hours after the beginning of the exposure, and of the next day, i.e. 32 hours after. Regarding urinary protein and hemoglobin content, no distinctive features were found in any group. As stated above, some significant signs were observed even in the 500 ppm group under the conditions of our experiments. Therefore, it seems that the MAC value of acetone of 500 ppm, determined by the Japan Association of Industrial Health, must undergo further consideration.

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There is a considerable amount of literatures on the therapeutic use of BAL or CaNa₂EDTA in inorganic mercury poisoning, but little has been studied on the effect of D-penicillamine, especially in organic mercury poisoning. The present authors experienced some cases of methyl mercury thioacetamide (CH₃HgSCH₂CONH₂) poisoning caused by dermal application of the compound for the treatment of a fungus disease of the skin. Signs and symptoms of these intoxicated cases has been found to be similar to those in cases reported by Hunter and Russel and those in so-called "Minamata disease". The present paper deals with results of administration of D-penicillamine in two patients who showed prominent nervous disorders.

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