232 MENDELISM 
on the Mendelian theory of inheritance when applied 
to populations. These figures are calculated on the 
supposition that there is random mating of the parents, 
but if there were a tendency for like to mate with like 
the correlation values would become still higher. Yule 
therefore concludes that ‘there is therefore no diffi- 
culty in accounting for a coefficient of 0°5 on the 
theory of segregation, but such a value probably 
indicates an absence of the somatic phenomenon of 
dominance. In the case of characters like stature, 
span, etc., in man this does not seem very improb- 
able.’ 
It is impossible to bring the present chapter to a con- 
clusion without some reference to the practical aspects 
of the Mendelian discovery. The progress of experi- 
mental research in this field during the last half-dozen 
years has been so rapid, that there is little ground for 
astonishment in the fact that only a small proportion 
of those to whom the discovery of the Mendelian 
method is of the very highest importance from a com- 
mercial point of view have yet arrived at any serious 
appreciation of it. The improvement of the breeds of 
cultivated plants and domestic animals is a subject of 
vital importance to the whole human race, quite apart 
from the question of the commercial profit which it 
represents for those whose business it is to be directly 
concerned with the process—the actual plant- and 
animal-breeders themselves. 
Hitherto the methods of amelioration which have 
been adopted have depended largely upon guess-work, 
