The second factor is methodological. Throughout the last half-century, and beginning with the pioneer work of Barrett and Kroeber, ethnographers have employed the informant method almost exclusively. It is not my intention to deprecate this procedure in any way or to imply that it has not proved an exceedingly valuable tool. I would like to suggest, however that it does carry certain limitations. I refer specifically to the inability of old men and women to remember and transmit _quantitative_ facts over a great span of years. On the other hand, _qualitative_ facts and ideas can persist in the mind with little or no blurring or alteration. Thus a man might retain clearly from his own memory, or through that of his parents, _where_ a village was located, what its _name_ was, and some of the _people_ who lived there. Yet he might have no clear concept whatever _how many_ persons inhabited the village or _how many_ villages were known to the tribe. This failure to retain and transmit accurate knowledge of number or mensuration becomes intensified if the informant is required to reach across an intervening period of unrest and confusion, both physical and mental, to an era of stability long since vanished. Yet this is just what the informant is asked to do when he tries to tell about the geographic and demographic conditions existing one or more generations prior to his own youth. I do not wish to advocate throwing out all informant testimony for these reasons--or, indeed, any of it. I merely wish to suggest that an undeviating adherence to literal statements of informants may on occasion lead to population estimates which are too low. The same discretion and criticism should be accorded them as in the other direction should be accorded to the statements left by contemporary white observers. THE YUROK The first exhaustive and scholarly attempt to assess aboriginal population was that of A. L. Kroeber (1925) in his Handbook of the Indians of California. He made a particularly careful study of and worked out his fundamental principles with the Yurok. Hence any reappraisement of the population problem in Northwest California must begin with a thorough examination of all the evidence pertaining to this tribe. Three primary avenues of approach are possible: ecological, ethnographic, and archaeological. It is proposed to deal here with the second, or ethnographic material. The principal sources are three in number; the pertinent chapter in the Handbook, the extensive monograph by Waterman (1920) and the village lists of Merriam (see Bibliography). All these investigators inspected the terrain and interviewed many informants during the decade 1900-1910. Hence their data have now become definitive.