He apparently began studying the inheritance of feeble-mindedness without theoretical prejudice, but with a practical end in view, to discover, if possible, the causes of feeble-mindedness so as to deal intelligently with the inmates of the Vineland (N. J.) institution with which he is connected. Goddard received inspiration and suggestion from the Mendelian principles which dominate the work of the Eugenics Record Office, but has published his observations in detail so that the reader may test by them any theory he likes. This method can not be too highly commended for it gives permanent value to the publication, however much prevailing theories may change. The book contains a detailed study of 327 "cases," each being the family history of a different inmate of the Vineland institution, as made out by trained investigators who visited the homes of the inmates and held interviews with their parents, relatives, friends and neighbors. English criticism of American work of this sort had prepared the reader to expect carelessness of method and inaccuracy in the accumulation of data, but Dr. Goddard is evidently on his guard against this. He goes very fully into the method of obtaining and verifying the data, and in doing so gives a very strong impression that the data are "reliable." His treatment of the data is also cautious but thorough, so that when he works his way to a conclusion it stands firmly established. The conclusions reached are numerous and important, but the one of greatest theoretical interest is this, that feeble-mindedness is inherited as a simple recessive Mendelian unit-character. This conclusion, so far as earlier publications were concerned, might be regarded as insufficiently established, but the evidence presented in this work renders it, I think, beyond question. Goddard was himself apparently considerably surprised at the conclusion reached. He had expected to find different kinds or grades of mental defect independently inherited as units and confesses to leanings toward views of the physiological independence of different mental functions, but his "cases" give him no evidence of such inheritance. He finds only that feeble minds are minds of arrested development in regard to all functions, and that different grades of feeble-mindedness correspond with different stages of normal mental development completely arrested. How different grades may occur in one and the same Mendelian unit is apparently a puzzle to Goddard, who does not attempt its explanation. It is indeed an absurdity to the "pure line" Mendelian, but not to one who appreciates the fact that Mendelian units are subject to quantitative variation sometimes continuous, sometimes discontinuous. An example of the former is found in the hooded pattern of rats,[4] of the latter in albinism and other Mendelizing characters which assume multiple allelomorphic conditions.[5] Pearson has steadfastly refused