402 Descendenz und Hybriden. 



discriminations, the imposing Correlation Table into which the 

 biometrical Procrustes fits bis array of unanalysed data is still 

 no Substitute for the common seive of a trained judgement. 

 For nothing but minute analysis of the facts by an observer 

 thoroughly conversant with the particular plant or animal, its 

 habits and properties, checked by the test of crucial experiment, 

 can disentangle the truth." 



„The tyro has confidence in the power of selection to fix 

 type, but he never stops to consider what fixation precisely 

 means. Yet a simple experiment will teil him. He may go to 

 a great show and claim the best pair of Andalusian fowls 

 for any number of guineas. When he breeds from them he 

 finds, to his disgust, that only about half their chickens, or 

 slightly more, come blue at all, the rest being blacks or 

 splashed whites. Indignantly, perhaps, he will complain to the 

 vendor that he has been supplied with no selected breed but 

 with worthless mongrels. In reply he may learn that beyond 

 a doubt his birds come from blues only in the direct line for 

 an indefinite number of generations, and that to throw blacks 

 and splashed whites is the inalienable property of blue Anda- 

 lusians. But now let him breed from his „wasters" and he 

 will find that the extracted blacks are pure and give blacks 

 only, that the splashed whites similarly give only whites or 

 splashed whites — but if the two sorts of „wasters" are crossed 

 together blues only will result. Selection will never make 

 the blues breed true; nor can this ever come to pass unless a 

 blue be found whose germ cells are bearers of the blue 

 character — which may or may not be possible. If the seiec- 

 tionist reflect on this experience he will be led straight to the 

 centre of our problem. There will fall, as it were, scales 

 from his eyes, and in a flash he will see the true meaning of 

 fixation of type, variability, and mutation, vaporous mysteries 

 no more." 



„But if, as is usual, the philanthropist is seeking for some 

 external application by which to ameliorate the course of 

 descent, knowledge of heredity cannot help him. The answer 

 to his question is No, almost without qualification. We have 

 no experience of any means by which transmission can be 

 made to deviate from its course; nor from the moment of 

 fertilisation can teaching, or hygiene, or exhortation pick out 

 the particles of evil from that Zygote, or put in one particle of 

 good. From seeds in the same pod may come sweet peas 

 climbing five feet high, while their own brothers lie prone upon 

 the ground. The stick will not make the dwarf peas climb, 

 though without it the tall can never rise. Education, sanitation, 

 and the rest, are but the giving or withholding of opportunity. 

 Though in the matter of heredity every other conclusion has 

 been questioned, I rejoice that in this we are all agreed." 



R. H. Lock. 



