Thus, Mr. Dugdale recognizes as underlying the testimony of mere figures a variety of factors essentially modifying the inferences which the former, exclusively viewed, would justify us in drawing, and endeavors to catch the ever-shifting influences of individual temperament, age, and environment. Heredity and sex, being fixed, are covered by the ordinary methods of statistical compilation. But as environment is the most potent of the varying factors which determine a career of honesty or crime, so heredity may be regarded among the fixed causes as the most contributive of effect in the same direction. “Heredity and environment, then, are the parallels between which the whole question of crime and its treatment stretches, and the objective point is to determine how much of crime results from heredity, how much from environment.” It is to the solution of this rather complicated problem that Mr. Dugdale addresses himself; and when we say it is complicated we do not exaggerate, so that we may be pardoned if, at times, in the course of the sinuous meanderings the question must necessarily take, we find ourselves at variance with some of his conclusions. Heredity is of two sorts: 1, that which results from cognate traits transmitted by both parents; and, 2, that which exhibits the modification dependent on the infusion of strange blood. This distinction is important as bearing on the question of heredity in its tendency to perpetuate propensities. If consanguineous unions intensify and transmit types of character with any degree of constancy and uniformity, we are justified in conceding that heredity is a criminal factor quite independent of environments, and that its relation to the solution of the problem why crime is so prevalent cannot be ignored. Now, the test furnished by the infusion of strange blood will enable us to judge whether constancy and uniformity of types are confined to consanguineous unions or not; for if, the environments remaining the same, a change of type is induced by non-consanguinity, then to the admixture of fresh blood alone can we attribute change of type, and so we must again admit the importance of heredity in the study of the case, but only to the extent and within the limits we shall hereafter point out. Mr. Dugdale is of opinion that both heredity and environment play a very important part in the career of the criminal, and it is with the design of sustaining his opinion that he has given us the history of the “Jukes.” Before we deal further with his conclusions we will here present a brief summary of the facts as related by him.