THE LAW OF PROGRESS 
far that their physical strength and fer- 
tility were greatly reduced, and their 
ability to care and look out for themselves 
under the stress of life was almost gone. 
Their weakened physical condition left 
them an easy prey to all the diseases that 
the species is heir to, and made them a 
burden to the man who bought them for 
the purpose of propagating for pleasure 
and profit. I have seen some of the lay- 
ing breeds of poultry inbred to such an 
extent that they were almost worthless for 
the production of eggs, and their offspring 
so weak in the early stages of life that a 
good percentage of them were unable to 
break out of the shell, and those that did 
succeed in getting out were so weak that 
it was almost impossible to raise them. I 
have seen some strains of some of the 
breeds of hogs inbred to such an extent 
that their fertility was greatly impaired; 
so much so, indeed, that large, strong 
litters were the exception instead of the 
rule. A good percentage of the scant 
litters died when born, or soon after, and 
often the mother also died. 
Darwin says on the subject of inbreed- 
ing: ‘‘T believe that their fertility has been 
155 
