The author has already reported, applying the method of action current, on the function of each leg-muscle and the manner of movement of leg, dorsal and abdominal muscles in several different standing postures in detail (this Journal, Vol. 62, p. 21, p. 61). The muscles which influence the movement of shoulder joint were investigated, the results of which are as follows:
A) Many descriptions have been made about the function of muscles for the movement of shoulder joint, using indirect methods, but the author's results obtained through direct method are different from theirs in the following points; a) m. trapezius pars transversea works when the scapula moves dorsalward, b) m. pectoralis major begins to work at the latter end of abduction, c) m. serratus lateralis does not work at internal rotation, but at external rotation, d) m. deltoides pars clavicularis does not work at abduction.
B) The way of contraction of the muscles at the following several postures of upper extremities; a) ad- and abduction, b) lift of arm forward and backward, c) horizontal circumduction:- The curves which show the degrees of contraction of each muscle were figured. These figures can not be obtained by the existing indirect methods.
C) The way of contraction of muscles at the normal standing posture.:- Of the muscles for movement of shoulder joint, m. trapezius pars descendens et transverse, m. deltoides pars spinata, m. supra spinam and m. rhomboides contract. Beside the muscles of shoulder joint, m. splenius capitis and m. semispinalis capitis are also contracting. And perhaps m. scalenus is working.
D) The way of contraction of muscles in the hanging posture without power in shoulder :- In this case m. trapezius pars ascendens, m. latissimus dorsi, m. rhomboides, m. pectoralis major, m. serratus lateralis, m. deltoides, m. supra spinam, m. infra spinam and m. biceps et triceps brachii are contracting.
E) The way of muscle contraction when the upper extremities is charged with a load (max.=40kg) (without power in shoulder):- M. trapezius pars descendens et transversa, m. deltoides, m. supra spinam increased their contraction in proportion to the weight of load. But m. biceps et triceps brachii does not work at all.
F) The way of muscle contraction in walking:- Upon movement of upper extremities forward, m. trapezius pars descendens et ascendens, m. serratus lateralis, m. deltoides pars clavicularis, m. supra spinam and m. infra spinam are contracting, while backward, m. trapezius pars transverse, m. latissimus dorsi, m. deltoides pars spinata and m. supra spinam contract.

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On June 25th, 1950, a fragment of humerus was discovered by Mr. H. YOSHIZAWA and Mr. T. KANAZAWA in No. 1 cave of No. 10 quarry of YOSHIZAWA Limestone Mining Industry Co. Ltd. in Ogano, Kuzu-machi, Aso-gun, Tochigi Prefecture. This specimen which lacks its trochlea and capitulum is a right humerus of a non-adult. His shaft is slender, but the opening in the lower part is equally developed as an adult's, and his anconeal fossa is located rather on the external side. Consequently, it is probable that this specimen is a human bone although it cannot be said to be normal. And further, a fragment of the shaft of a woman's left humerus was found in the same cave on Aug. 21st, 1950. The specimen is also young and resembles the shaft of chimpanzee though it has been defaced by running water. However, the osteological characters show that it is also a human bone. It may safely be said that these two specimens described above are the fragments of bones of the original human beings whò were akin to the ape.
The deposit of this cave presumably was drifted by flood into this cave with the human bones together with other natural remains, it is guessed. It was piled up against a heap of loam, because this cave is covered all over with loam which is found widely in the Kanto area. I am assured that the geological age of this layer is the Middle Pleistocene or Lower Pleistocene from the items of other fossils which have been found with these human bones. The following fossils have been found in this cave:
Mammals: Mogera wogura wogura, Urotrichus talpoides hondonis, Chimarrogale sp., Apodemus sylvaticus speciosus, Canis lupus lupus, Ursus sp., Megaceros sp., Cervus praenipponicus, Palacoloxodon nanmanni, Macaca fuscata.
Birds: Corvus sp., Fringilidaea gen. et sp. indet.
Amphibia: Bufo sp.
Reptilia: Clemmys sp., Natrix sp.
Moreover, a piece of a human left femur was found in this cave on July 25th, 1950. I should like to name it Homo? Tokunagai as a type-specimen. I am going to report on it in another article. It is my belief that the two fragments above described belong to the same species.

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Hitherto the study on walking has been limited to its mechanical analysis by means of photography, the efficiency of energy metabolism obtained by gas analysis, and the sole pressure etc.; the action of muscles has been little studied. The author tried to research when and how the muscles work in walking.
The action current of muscle was then applied as an approach to my study ; two fine silver needles (diameter 0.2mm) chosen for electrode, were put into the muscle, the action current of which was amplified and recorded in the same way as in his previous report (This Journal Vol. 61, No. 692, 1950).
The swing and stance phases of foot were investigated by the electrical circuits through phosphor-bronze contacts attached on the sole (Fig. 2). And the changes of angles at the coxal, knee and foot joints, which result from their extension and flexion, were measured from a moving picture (Fig. 1). Shifts of the centre of gravity of body and changes of the sole pressure were cited from the study of O. FISCHER (Fig. 3). The writer tried to explain the mechanism of walking by means of these Electromyogram (E. M. G.) obtained experimentally (Fig. 5). The results are as follows:
1. Two-articulated (joint) muscle has something to do with the smoothness of movement, and is not so powerful as one-articulated one and easy to fatigue.
2: The constant shifts of the centre of gravity in walking makes the holding of posture so delicate which is cooperatively operated by the two antagonistic joint muscles, for example M. rectus femoris and biceps femoris. Also by fixing of knee is effected the extension of M. glutaeus maximus at the end of stance leg.
3. It is remarkable that M. sacrsopinalis, in the upper body, shows the stretch reflex by the reflexive contraction.
4. In the middle of stance phase we take notice of a valley in the E. M. G. This is considered to show the resting time.
5. At the end of stance phase, we find the many muscles working cooperatively and especially, the shifting of the centre of gravity is caused by a series of muscles from the pelvis on the side of stance leg to the neck on the other side and this is connected with the out-rotation of foot and the contrary swing of arm and leg.
6. At the beginning of stance phase, the muscle series consisted only of extensors, M. glut. max., rect. femo., and gastrocnemius work. On the contrary, at the beginning of swing phase we see only the flexors series, M. iliopsoas, biceps femo. and tib. ant., working.
7. Reciprocal innervation is proved in the case of one-joint muscles and not in cases of two-joint muscles.
8. The waist reflex is remarkable in all reflex postures in walking.
9. The neuromuscular unit works in very small cycles, for example, 10 or so even in M. vast.fibularis. The long continuance of walking is affected by this and reciprocal innervation and reflex.
10. Compared with cases of riding a bicycle, muscles show far more natural working in walking which is by far suitable to muscle. E. M. G. in the case of bicycle is shown in Fig. 6.

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The final object for our studies on population problems is how to improve the disharmony between the man and his environment from socio-biological point of view. The author tried a historical review on population theories ; most of them were approached from socio-economical view of point, but the biological considerations were always employed at the base of them. We have seen two outstanding debates concerning the population problems after the War in Japan ; the one being in relation with the population capacity and the other with the population control. The former is to inquire into the limit of population in which a established level of living could be maintained, and to make clear the real feature of overpopulation, especially in the light of the relationship between modern industry and rural population. The results of these inquiries had an effect to turn the general attention toward the social security system. The latter subject was taken up as a means to secure the people from the financial poverishment and sociological as well as biological deficiencies which would result from the free birth. Some fundamental researches were conducted by the Research Institute of Population Problems in Welfair Ministry, including the survey on the birth control practiced among urban and rural population, together with the status of sexual behavior of married couples. In Japan there are two characteristic types of society, the modernized urban society and the rather primitive rural one, and as a whole the increasing population confined in a limited territory presents serious fact which demands immediate and drastic study on and measures for population problems for the practical solution of the situation. The population problems involves many important subjects which are to be inquired by anthropologists from the view point of this field of science.

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