The writer carried out some investigations in order to estimate the amount of groundwater flow in Koromo Basin, the Yahagi River valley. He surveyed the geology of the basin by means of the electric resistivity method, using an apparatus of the Electro-Technical Laboratory type (Fig. 1). Koromo Basin is drained by Yahagi Valley and is filled up by granite, Tertiary formations and Diluvial (? ) and Alluvial deposits. Alluvial sand and gravel layers are of great importance in the study of the groundwater hydrology, for they now constitute the source of most productive and intensively used groundwaterr supply.
About 110 wells were examined and a groundwaterr contour map was obtained (Fig. 2). From this map, direction and gradient of the groundwater flow were procured. He evaluated permeability coefficient k by Tiem's E method and discussed its accuracy by other methods. Using these data above mentioned, he calculated groundwater amount through a valley section and obt_??_ined 2.63 m³/sec as the total groundwater discharge through a valley section (Fig. 3. 4. 5. Table 1. 2. 3).
This amount answers to a relative discharge of 0.236m³/sec/100km². It is not without interest that this sum is almost equal to the relative ordinary discharge of the Yahagi River:-i. e. 0.270m³/sec/100km².

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On the south side of the River Usui, the erosion surface of Iwanoya Hill slopes from NE to SW, while the terrace plains of Usui slope from SW to NE, so that they form the “Hinge feature”. (Fig. 1, Fig. 2)
The writer researched the distribution of terrace gravels, from which he presumed that the River Usui probably flew on the south side, of the hill and r n into the valley of Kabura. (Fig. 3) As it is presumed that, the western part of Iwanoya Hill was as high as the eastern part, when the River Usui flew on the upper terrace plain afterr changing its course, so it seems that the formerr part suffered more denudation than the latter.
Moreover, the terrace plain which remains highest in the western area of this region, is covered by gravel beds, and the north-eastern part of the hill which also remains higher in that area is chiefly composed of conglomerates, while the lowerr western part is composed of soft mud stones and sand stones. From these facts the writer concludes that such “Hinge feature” may be interpreted by the difference of resistance to erosion which is effected by the distribution of gravels.

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Three areas, each. with its characteristic agric_??_ltural operating system, which have been delimited in the preceding papers, are compared concerning the important sources of farm income. The date used ai e derived f om the Agricultural Census 1947, and the Agricultu, al Summer Survey 1941. Among the sources of cash income the most gene, -al items of the first and second order for farms are determined in. each section. The results are as follows.
_??_
In the paddy field section the paddy rice, and in the upland field section α the tobacco is the main resource of cash income respectively. Forr upland field β paddy (including land) rice makes the most important item now, but in about 1940 it Was sericulture instead. Among the items of the secondary order which indicate only the situation about 1940, the predominance of wheat and barley over others is noteworthy throughout three sections

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In the course of following the developement of acclimatization theory, the present writer has found three characteristic periods in its historical background. The first is the period after the middle of 19th century when the term “ acct i rnater” was first used i n France and the scientific study was initiated principally as a means of French colonial policy. The. second is the period of the laterr p_??_rt of 19th century when racial acclimatizability was considered as a major problem that influences the balance of power. in Europe concerning the division of Africa. He has already dealt with these periods in his formerr parts of this study.
The third period is discussed in this thesis, which is divided into five chapters. Chap. I is the bibliography. Chap. II points out its connection with the world-population problem. World War I began in an anti-Malthus at-mosphere, but the post-war population theory may be said a reversion to the Malthusian theory. Europeans' view of surplus population, arising out of the difficulty of economic rehabilitation, strongly influenced by the slightest absolute increase of population, was that they pinned their hope on the population-capacity of the tropics, because that of temperate zone would be saturated sooner or later.
Chap. III is developed upon the world-food problem closely related to the population theory in the preceding chapter. Then the food export from undeveloped areas reaches its limit, it should be the last stage of world-population capacity. Some scholars were conscious that Europe was fastaapproaching this stage and planned emigration into these areas as its solution, hence the problem of acclimatization of the white aboriginally settling down in the temperate zone.
Chap. IV deals with the rise of emigration problem. Before World War I the surplus population of Europe found its outlet in America. H wever, when Americans became conscious of the disappearance of frontiers, they awake ned to the population problem. It resulted in the execution of Quota Law in 1921. Consequently, many European and American geographers diverted their attention to non-temperate areas as a measure of rationally dealing w th European emigr_??_nts. As to whether tropical resources were promising or not, various op_??_nions prevailed, in which emigration. of the white to the tropics was emphasized by those who recognized the importance of the tropics.
Conclusion. The study of acclimatization in this third period aims at a solution of European surplus population. If the surplus population in Europe and such a view itself are the products of highly-capitalistic society of Europe, the acclimatization-theory also should be its product. Besides, the emigration problem which met with an unprecedented revolution should be the immediate cause of the need of study of acclimatization in this period.
Historically to clarify the recognition of this problem is the starting-point of a fresh study on this theory. The present writer will. not adhere to the old recognition of it.

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