[page number] -2- [end page number] Mr. B. R. Winslow December 2, 1919. It cannot be said that heredity plays no part in congenital rickets (see Delfino, 1913, Fortschutte auf den Gebiete der Rontgen Strahlen, Bd. XX, p. 577.) Cretinism has an hereditary factor just as tuberculosis has; there is however also an exciting cause external to the organism. Polydactylism usually is inherited as a dominant trait in various mammals and birds, as well as in man, but it is not always obviously hereditary. Bent fingers are usually a typical dominant trait, as our files show; however as in your case, the grade is perhaps determined more by external than internal factors. Crooked fingers combined with syndactylism (a more extreme degree) is found also in poultry as a dominant trait (see publications of the Carnegie Institution of Washington on inheritance of poultry, by the present writer). Bending of the finger may involve bending of the shaft also, as Lovett (1915) has shown in the case of rickets. No doubt the extent of damage done by malnutrition upon development varies with the degree of malnutrition and also with the degree of resistance of the developmental factors to the malnutrition. I trust this covers the points you have in mind. You will see that we are still feeling our way in regard to the various factors upon which the end result depends in the cases that are of especial interest to you. If you care to deposit with this office the name and address of the boy who is the propositus of your charts (IV-15), we