330 SCIENCE PROGRESS 



the number of great characters common to all the individuals of 

 *he race, each individual therefore shows a number of differences 

 in these characters which are common to a section of the race 

 but not to the whole race ; a smaller number of smaller differ- 

 ences which are common to a smaller number of individuals ; 

 and so on to those differences which are peculiar to himself 

 alone. 



As these considerations lead me to believe that but com- 

 paratively few characters are transmitted from pprent to 

 offspring in the Mendelian manner, so I am convinced that 

 Galton's law of Ancestral Inheritance can only be applied, even 

 in its broadest and most "averaging" sense, to precisely the 

 same group of characters. The overwhelming bulk of our 

 characters come equally through, not from, both parents. Half 

 of them certainly do not come from each. On the other hand, 

 it does not seem improbable that, on the average in a large 

 number of individuals, small differences may be inherited 

 approximately half from each parent, a quarter from each 

 grandparent and so on. It cannot quite work out at this rate, 

 however, for each individual in the ancestry makes some 

 addition to or subtraction from what he or she inherited from 

 the parents. The individual contributes his own variations. 

 The "half" contributed by each parent is made up of two 

 " quarters " contributed by each grandparent, plus the variations 

 of the parents. Without this, evolution would have been im- 

 possible. 



I have elsewhere put forward the view that the characters 

 that are transmitted in the Mendelian or alternative manner are 

 those which have comparatively recently arisen as variations in 

 individuals. 1 Those that have become so established as to be 

 common to all the individuals of a race do not behave as 

 Mendelian characters when crossed. To make my meaning 

 clear it is here necessary to deal with some features of the 

 Mendelian experiments. One of the most important of these is, 

 that the overwhelming majority of them have been made with 

 domesticated races. Here I must refer to that very able 

 exposition, " The Logic of Darwinism," by Mr. Archer Wilde. 

 I imagine that almost every one who gives the matter serious 

 consideration must agree with him that it is quite unreasonable 



1 Essentials of Cytology (Constable, London, 1907) ; Hereditary Characters, 

 1910. 



