Between tne Ainu race which is said to be doomed to the sad fate of ultimate extinction and us Japanese there has been a close, inescapable blood relationship for 3000years. No studies upon dependable records in connection with this matter go back more than two hundred years. Since 1804 (Bunka 1) many studies have been made on the Ainu. It is recorded that their number showe 1 a decided eecline from 21, 697 to 16, 136 in the fifty years to 1854. The causes of this decline may be set down as follows: (1) The exploitation and misuse of the Ainu population following their subjugation after the rebellion of 1669 (Kanbun 9). 2) The spread of syphilis, alcoholism and tuberculoAs. (3) The decrease in deer and salmon, their chief articles of food. (4) Acute epidemics of cholera, small pox etc. (5) The lack of knowledge of hygiene leading to bad physical results and (6) Natural catastrophes and economic adversity.
From about 1868 to 1912 there was a regular and natural development, but another sharp decline in pmulation occurred between the years 1915 and 1926. This decline cannot be said to be traceable to Japanese oppression, but rather to such factors as economic depression, changes in the standard of living, continued spread of syphilis and tuberculosis, the transfer of Ainu domiciles (seki) into Japanese families and their general spiritual depression.
Recently a falling off in the increase in tuberculosis can be perceived but there has been no perceptible corresponding decline in the spread of syphilis. Since 1927 a gradual increase in Ainu population can be noted. In 1935 a study was undertaken of the Ainu when the constitution of their age groups was found not to be out of the normal, on the whole.
It is very difficult to classify the Ainu according to such anthropological criteria as customs, habits, language, burial practices, relics, ruins, festivals, family insigniamon, foods, style of buildings, wells, latrines, furniture, weapons and religious traditions. It has also been proven difficult to classify them according to blood tests and anatomical measurements In the Tokugawa times they were classified according to fishery districts, governmental divisions, economic relationship with other groups and residence whether in mountain, river valley or beach communities. Having in mind all this body of previous practice, it is the writers proposal in this paper to divide the Ainu population into the following four groups:
(A) Those Ainu who have had the closest relation with the J apanese, living in the districts of Oshima, Hiyama and Shiribeshi.
(B) Those living along the Ishikari River up to Cape Soya and across to the Okhotsk Sea, including those in the Kamikawa, Sorachi and iciland districts.
(C) Those living in the Abashiri, Nemuro and Kushiro districts extending into the Chishima bounded by the eastern half of the Okhotsk shore and the Pacific coast-line.
(D) hoso living in Tokachi, Hidaka and Iburi where the climate is comparatively mild making thoso regions the easiest in which to live.
When studies are made according to the above classification, it is found that the Ainu population of class (A) is the farthest from normal in respect to the age group curve. The population of classes (B) and (C) are similar while class (D) most nearly approximates the normal age group curve.
There are several reasons why the Ainu of class (D) come most nearly to normality in regard to age grouping.

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Als Material für die Untersuchungen bedient. n wir uns unsere einigen Aufzeichnungen über die Familien in Kanazawa-shi (als Stadtgemeinschaft) and in einer gewissen Bezirke in Ishikawa-ken (als Lanclgemeinshaft).
Die Unterschiede in der Häufigkeit der Zwillingseburten bei den verschiedenen Blutverwandten sind in der folgen-len Tabelle gegeben;
Wie oben gesehen, die Häufigkeit der Zwillingsgeburten bei dem Stamm der Zwillingen selbst ist gräser als bei der allgemeinm Population, damit kann man die Tatsache, dass die Anlage der Zwillingsgebu ten erhlich ist, ohne weiters klar machen.
Die Erhöhung der Zwillingshäufigkeit bei den Geschwistern als bei Vätern, Müttern und Kindern der Zwillingseltern, aus meirem Material ziemlich Ficher nachweisbar ist, stimmt mit der Annahme üherein, dass das Merkmal ein rezessives sei,
Wir besähbftigten uns weiter mit der Frage des Erbgang der Zwillingsanlage nach Cer Methode von Crutius und v. Verschuer. Wir wollen aber den endgultigen Schluss hier zurückhalten, weil die Manifestationswahrscheinlichkeit der Merkmale bei unserem Material nicht so sicher konstatierbar war.

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