PLANT HYBRIDIZATION BEFORE MENDEL 259 



mental character as a law of evolution, describing the average 

 trend of circumstances when a large number of individuals are 

 taken together without reference to sex. It is an expression of the 

 law of bodily appearances, and only pretends to describe the con- 

 dition in the germ cells, as Galton himself observes, insofar as 

 the bodily characteristics are the outward expression of an in- 

 ternal germinal condition, which Galton assumed, reasoning re- 

 versely, must be the case, else why should there be an average 

 inheritance of the color-characters of the nature described. How- 

 ever, Galton's expectation that his discovery might be available 

 for practical breeding purposes has not been entirely justified. 

 It has indeed proved the value of pedigree records for live stock, 

 and the general truth of the axiom that "like begets like." In a 

 word, in the light of our present understanding, "Galton's Law" 

 is largely an average mathematical expression for the operation 

 of the law of dominance. It is the most important effort, however, 

 during what may be called the "Darwinian period," at obtaining 

 an exact statistical expression of the law of inheritance in 

 populations. 



BIBLIOGRAPHY 



Galton^ Francis. 



(a) Natural Inheritance. London and New York, 1889. 



(b) The average contribution of each of several ancestors 

 to the total heritage of the offspring. Proc. Roy. Soc. 

 61 1401 . 1897. 



Goldschmidt^ Richard. 



Einfiihrung in die Vererbungs-wissenschaft. 4th ed., Leipzig, 



1923- 



