CHAPTER V 



REVERSION AND ALLIED PHENOMENA 



" A man can never deny his ancestry." LAWS OF MANU. 



" Evolution ever climbing after some ideal good, 



And Reversion ever dragging Evolution in the mud." TENNYSON. 



i. What is meant by Reversion. 



2. Suggested Definitions. 



3. Theoretical Implications. 



4. Phenomena sometimes confused with Reversion. 



5. " Skipping a Generation." 



6. Mendelian Interpretation of Reversion. 



7. Reversion in Crosses. 



8. Reversion of Retrogressive Varieties. 



9. Interpretations in Terms of Reversion. 



10. Further Examples of Reversion. 



i. What is meant by Reversion 



MOST evolutionists indeed, most naturalists have ranked 

 reversion as one of the facts of inheritance. Thus Darwin 

 said (1881) : " Any character of an ancient, generalised, or 

 intermediate form may, and often does, reappear in its descend- 

 ants after countless generations." Wallace, Spencer, Galton, 

 and Weismann have all used the concept " reversion " as a 

 convenient way of summing up a universally admitted series of 

 cases, where organisms exhibit ancestral traits which their 

 parents did not possess. As a descriptive term for summing up 

 these cases, the word " reversion " is useful, convenient and, it 



119 



