The study of the Laws of Heredity, as conducted in the preceding papers, has resulted in a definite conclusion, it is true, but in a conclusion as to tendencies only; and whatever facts we may ascertain in the family history of a patient, however numerous and however damning they may be, they can never warrant us in inferring anything whatever with respect to that patient, beyond the existence of a tendency in one direction or another. To ascertain how far, and in what proportion, these tendencies, in so far as they concern the Structure of the Organism, have become actualities, recourse must be had to the study of the Physique, which is the outcome of the combinations, and conflicts of the laws of inheritance. Or, in other words, the Physique is the form which the organism has assumed under the action of the developmental forces.