Atavism by Seeds and Buds. 105 



But before I proceed to examine these two forms of 

 atavism more closely, I think it desirable to state that I 

 here use the word ''atavism" in its narrower sense, for 

 in its wider sense it embraces so large a group of phe- 

 nomena that it would not be possible to deal with them 

 all within the limits at my disposal. It seems worth while 

 to indicate the more important of these types because they 

 are often confused with one another and because results 

 obtained with one form are often taken to apply to an- 

 other, simply because they both go by the same name. 



We must first of all draw a sharp distinction between 

 atavism as applied to variability and as applied to muta- 

 bility. In the first case we are dealing with the phenom- 

 ena presented by a single heritable character ; in the latter, 

 with the conflict of two or more. In the improvement 

 of races the offspring do not resemble the selected pa- 

 rents, they always revert partly towards the mean of 

 their ancestors. We are of course dealing in such cases 

 with the phenomenon of regression which was fully dis- 

 cussed in the first volume (pp. 82 and 120) ; and it 

 would be better to refer to all those individuals of less 

 value which are eliminated in selection as regressive and 

 those which exceed the level attained by their parents as 

 progressive. But it is customary to call the former atav- 

 ists; and, as a matter of fact, they exhibit the degree of 

 development of the characters in question as it was mani- 

 fested by their grandparents and more remote ancestors, 

 and not as in their parents. They could perhaps be 

 called ''curve atavists," since this term does not suggest 

 a reversion beyond the curves in question.^ 



The most fascinating section of the subject of atav- 

 ism is that which deals wath so-called "youth" forms 



^ See the pedigree of the many-rowed maize, Vol. I, p. y^,. Fig. i8. 



