It is already a well-known fact that the NMU of the skeletal muscles in man is composed of two groups of quite different properties, that is, the K- and T-NMU. In animals, however, numerous studies have been made without reaching any decisive differentiation of the NMU, because of the difficuties in inducing the animals to a voluntary muscular movement. In maintaining a certain standing posture, which is regarded as one of the fundamental stances in the research on the function of the skeletal muscles in animals, the NMU obtained has always presented the T-NMU. The present study has been attempted to clarify the fact that the muscular movement of animals is maintained not only under the action of the T-NMU, controlled by the subcortical or spinal nervous system, but also under that of the K-NMU, which has been evoked by the activity of the motor area in the cerebral cortex. The procedure is as follows. 1.The sciatic nerves of young dogs and goats were deafferentated by cutting the dorsal root and ganglions on both sides of the spinal segment of L₆, L₇ and S₁. After the serious extension of the hind limbs caused by the operation wore off, the animals were exercised to support the hind half of the body on their feet. 2.Observation of the action potential of the gastrocnemius muscle was repeated every two weeks for period of 2 or 3 months. Using the numerous time-series of the discharge intervals of single NMUs, the average τ^^- and the standard deviation S were culculated, and then the τ^^--S points were graphed for differentiation of the two kinds of NMU. The following results were obtained. 1). The exercise, for two or three weeks after the forced extention of the hind limbs was abolished, enabled the dogs to stand for a few minutes on their tarsal joints with the help of the trainer. The τ^^--S points then scattered between the K- and T-curve, which is defined at the end of this experiment. 2.) After continuation of the exercise for a further period of 2 or 3 weeks, the animals could stand voluntarily on their hind limbs, touching the tarsal joints firmly on the floor. The τ^^--S points of the time were clearly divided into two groups, excluding the location of the K-NMU they were markedly biased to the left side. 3). 1 or 2 months later, the dogs learned to stand on their feet, keeping the tarsal joints away from the ground, and to walk and to run around. The τ^^--S points then distributed along the K- and T-curve without overlapping. 4). From the results above-mentioned, it was ascertained that the NMU of the skeletal muscles in the dog is composed of the K- and T-NMU. 5). Nevertheless, it was impossible to discriminate between the two NMU in the case of the goat, in which the legs remained inactive up to the time of their death without any improvement in the mechanical use of the limbs, despite carefull management and constant exercise.

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From the view point of practical application of electromyography, it is of great value to determine whether the discharge of NMU increases gradually in frequency to correspond to the progressive increase in the magnitude of contraction in a muscle. Using two adult dogs, the characteristic of each skeletal muscle was studied during quiet standing or while the animals were drafting loads on variously inclined board. It has been proved that the magnitude of contraction in the gastrocnemius muscle increase gradually, when an adding series of load is chosen, combined with the increase of the inclination of the standing board. Statistical analyses were made on the relationship between the magnitude of the integrated values of the action potentials and the averages of the discharge-intervals of single NMUs, obtained simultaneously from the same muscle. When the average of the discharge-intervals are plotted against the integrated values of the action potentials, the resulting diagram indicates a tendency toward the decrease of the average interval to occur with the larger magnitude of the integrated value. Nevertheless, a linear relationship is found only in the range of relatively weak contraction. The regression equation departs from the linearity unless the integrated values are transformed to a logarithmic scale. This result means that the regression equation between the integrated values and the average discharge-intervals is a expotential function. When, however, the magnitude of contraction is determined by a single average of the discharge-intervals of a NMU, it is not possible to give correct information. This is because the individual average intervals are distributed over a wide range, even though the shortening of a muscle is kept at a constant strength. In practice, therefore, it is nessesary that the preliminary experiments are carried out to determine the fiducial limits, at a probability of 0.95 or 0.70, of the average intervals corresponding to the progressive increase of the magnitude of contraction, that is, a control chart would be needed. The ranges in the control chart must be chosen so that there is no overlapping between the adjoining limits; for example, the range from 60 to 70 ms would correspond to strong, that from 70 to 80 ms to a moderate contraction, and so forth. An estimate of the strength of a certain muscular activity is made by plotting several numbers of the average intervals of NMU occurring in the same muscle, and obtained during an unchanged contraction, on the control chart. Accordingly when the range involves a large number of the plotted averages, the strength of the contraction of a muscle can be determined.

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Phosphorus 32 was administered to the chicken for the study of radiation injury by internal irradiation by P³². Following is the result of our experiment. 1) As the result of a single administration of doses beyond 3μc/g, we found the chicken died and 80% of the animals as the result of a dose of 5μc/g and all of them in the case of a dose of 10μc/g died. 2) The curve of the rate of weight gain was inhibited according to the increase in the dosage of P³². For example, the inhibition was slight for a dose of 1μc/g (minimum dose tested), while the body weight did not increase at all in the case of 10μc/g (maximum dose tested). 3) Weight of organs changed by the irradiation. It decreased in spleen, thymus and testicle, on the contrary it increased in liver, kidney and heart. 4) Food intake was inhibited by doses beyond 5μc/g, but water intake was not affected by any dose tested. 5) There was no remarkable change to be noted in body temperature, respiration rate and heart rate. 6) Blood hemoglobin, hematocrit value showed a remarkable decrease, and in some cases it decreased to about 10% of the control value. 7) In the study on plasma protein, the increased value of albumin was observed the initial period after administration, and a durated increase of globulin was observed over a period of twenty days. 8) Blood sugar after administration of P³² gradually increased in the course of time. 9) The results of the glucose tolerance test showed delay of recovery on the curve of glucose tolerance curve. As above mentioned, the internal irradiation by P³² affected remarkable the hematogenic organ, while other organs were noticeably less affected. In conclusion, presumptions of irradiated doses described in previous paper met with our experiment.

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