1900.] on Facts of Inheritance. 359 



the varying prepotencies of sex in respect to different qualities are 

 also presumably eliminated." 



This law of ancestral inheritance, which states that each parent 

 contributes on an average one-quarter, each grandparent one-sixteenth 

 and so on, rests on researches on human stature, etc., and on colour 

 in Basset hounds, but Prof. Karl Pearson trusts it even more because 

 of its success in predicting results. He is very enthusiastic on the 

 subject, and finishes a paper on Galton's law with the following 

 words : " It is highly probable that it is the simple descriptive 

 statement which brings into a simple focus all the complex lines of 

 hereditary influence. If Darwinian evolution be natural selection 

 combined with heredity, then the single statement which embraces 

 the whole field of heredity must prove almost as epoch-making to 

 the biologist as the law of gravitation to the astronomer." * 



The aim of this lecture has been to present in brief compass a 

 statement of the leading facts of inheritance, which should be clear 

 in the minds of all. I have said nothing in regard to the transmissi- 

 bility of acquired characters, for this cannot be ranked at present as 

 an established fact, and I have left some other doubtful points un- 

 mentioned. Allow me in conclusion to make this simple remark. 

 The study of inheritance leaves a fatalistic — almost paralysing — 

 impression on many minds, especially perhaps if it be believed that 

 the acquired results of experience and education — of " nurture," in 

 short, cannot be entailed upon the offspring. To some extent this 

 fatalistic impression is justified, but it is well that it should rest upon 

 a sound basis of fact and not on exaggerations. In a sense we can 

 never get away from our inheritance. As Heine said half bitterly, 

 half laughingly, " A man should be very careful in the selection of his 

 parents." On the other hand, although the human organism changes 

 slowly in its heritable organisation, it is very modifiable individu- 

 ally, and " nature " can be bettered by " nurture." If there is little 

 scientific warrant for our being other than sceptical at present as to 

 the inheritance of acquired characters, this scepticism lends greater 

 importance than ever, on the one hand, to a good " nature " to secure 

 which for offspring is part of the problem of careful mating ; and, on 

 the other hand, to a good " nurture " to secure which for our children 

 and children's children is one of the most obvious of duties, the hope- 

 fulness of the task resting upon the fact that, unlike the beasts that 

 perish, man has a lasting external heritage, capable of endless modi- 

 fication for the better. 



[J. A T.] 



* Reference should, however, be made to Mr. Pearson's recent piper (P. Roy. 

 Soc. lxvi., 1900, pp. 140-161) on The Law of Reversion. 



