No doubt there is some substance to these objections, but they contain rather a modicum of truth than an inclusive presentation of the facts relevant to the case. As to (_a_), the races of man are, after all, more alike than unlike, and the evidence drawn from the experience of any one racial stock or mixture is not to be disregarded as having no significance for the probable course of things experienced by any other racial stock during a corresponding interval in its life-history. Yet there is doubtless a wide and debatable margin of error to be allowed for in the use of all evidence of this class. As to (_b_), by virtue of the stability of racial types the populations of existing communities of the lower cultures should be today what they were at the outset, in respect of the most substantial factor in their present situation, their spiritual (instinctive) make-up; and this unaltered complement of instincts should, under similar circumstances and with a moderate allowance of time, work out substantially the same general run of cultural results whether the resulting phase of culture were reached by approach from a near and untroubled beginning or by regression from a “higher plane.” So that the existing communities of savages or lower barbarians should present a passably competent object lesson in archaic savagery and barbarism whether their past has been higher, lower, or simply more of the same. All this, of course, assumes the stability of racial types. But since, tacitly, that assumption is habitually made by ethnologists, all that calls for apology or explanation here is the avowal of it. The greater proportion of ethnological generalisations on this range of questions would be quite impotent without that assumption as their major premise. What has not commonly been assumed or admitted, except by subconscious implication, is the necessary corollary that these stable types with which ethnologists and anthropologists busy themselves must have arisen by mutation from previously existing types, rather than by a long continued and divergent accumulation of insensible variations. A result of avowing such a view of the genesis of races will be that the various races cannot be regarded as being all of the same date and racial maturity, or of the same significance for any discussion bearing on the higher cultures. The races engaged in the Western culture will presumably be found to be of relatively late date, as having arisen out of relatively late mutational departures, as rated in terms of the aggregate life-history of mankind. Presumably also many of the other races will be found to be somewhat widely out of touch with the members of this Occidental aggregation of racial stocks; some more, others less remotely related to them, according as their mutational pedigree may be found to indicate.