There is no really great scientist in biology at the present moment who teaches the hereditary transmission of acquired characteristics. Modifications of the organism that become matter for heredity have existed for many generations and we cannot tell just how they began. There is no doubt that there is some hereditary influence, for insanity in the same family is likely to keep recurring in successive generations. More than this, affections of certain less important organs are evidently a common trait in certain family strains. There is no doubt that in some families stomach affections are the rule in successive generations. It is very hard to say, however, just when such defective organisation became a family trait. The tendency to nervous affections is undoubtedly a similar family affair. Certain affections have been hereditary traits for many generations. An excellent example of this is the so-called Huntingdon's chorea, which several generations of American doctors, of the name of Huntingdon, by following carefully the history of certain families on Long Island, succeeded in tracing through four generations. The habits of life of a father or a grandfather may so weaken the physical constitution of his descendants as to make them less capable of resisting infections in the physical order, or in the moral order of withstanding trials and temptations, and the allurement to abuse of nervous excitement to which they may be subjected. That some acquired pathological condition, however, as stomach trouble, or heart {123} trouble, or affection of the liver or of the brain, should be directly transmitted, is quite as nonsensical as that the loss of an arm should be a subject for hereditary transmission. On investigation it will be found that the pathological conditions of immediate ancestors are themselves only a manifestation of family traits that have existed for many generations. The possibility of inheritance must therefore always be borne in mind. We are utterly unable as yet to understand how such family traits are originally developed, since, in ordinary experience, at least, acquired characteristics are not the subject of inheritance or transmission, and consequently it becomes difficult to understand how they ever became impressed upon the family constitution.