INHERITANCE 199 



body of the parent can affect the reaction of the offspring to 

 the same stimulus. This beHef, at one time universally held, 

 still awaits confirmation by properly controlled experiment. If 

 we attempt to analyse in exact terms the belief that '* acquired 

 characters " are inherited, it appears to involve two separable 

 issues : (a) whether the inhibition or destruction of a characteE 

 is accompanied wholly or partially by the destruction of its 

 material antecedent in the germ cells ; (b) whether, if a stimulus 

 of a given magnitude is required to call forth a given response, 

 the application of that stimulus to the parent carries with it 

 the possibility of evoking the corresponding response in the 

 offspring with a stimulus of smaller intensity. Without 

 committing oneself to a dogmatic negative, it can be stated 

 as a matter of fact that in a good many cases the answer is 

 certainly in the negative (within the limitations of experiment 

 on these lines), and that in no single instance where a positive 

 answer has been given has independent and rigorous 

 reinvestigation confirmed the observations recorded. The 

 principle of economy of hypothesis is therefore best preserved 

 if the Lamar ckian principle is eliminated from consideration, 

 when the bearing of hereditary transmission on other branches 

 of experimental biology is under discussion. 



Further Reading 



GoLDSCHMiDT. Mechanism and Physiology of Sex Deteniiination. 

 Methuen. 



Morgan. The Physical Basis of Heredity. Lippincott. 



Crew. Introduction to the Science of Animal Breeding. Oliver and 

 Boyd. 



East and Jones. Inbreeding and Outbreeding. Lippincott. 



Morgan, Bridges and Sturtevant (1925). The Genetics of Drosophila. 

 Bibliographica Genetica (the Hague), vol. 2, 



