160 Inheritance of Acquired Characters 
so on, can not constitute any satisfactory proof in the 
absence of reliable observation and confirmation of the 
facts. 
Darwin draws especial attention to the inheritance of 
characters acquired by domestic animals. ‘The domes- 
ticated duck,” he remarks, “flies less and walks more than 
the wild duck and the bones of its anterior and posterior 
limbs have become respectively diminished and increased 
in comparison with those of the wild duck. A horse is 
trained to certain paces and the colt inherits similar con- 
sensual movements. The domesticated rabbit becomes 
tame from close confinement ; the dog intelligent from as- 
sociating with man; the retriever is taught to fetch and 
carry; and these mental endowments and bodily powers 
are all inherited.” 127 
These examples, one must admit, deserve all considera- 
tion, especially the first. But one encounters here the ob- 
jection which can always be raised against such examples: 
As functional adaptation has a great modifying influence 
upon the organism, how can we be certain that the greater 
size of the bones of the legs in the domestic duck really 
springs from inheritance of acquired characters rather 
than from the daily exercise of the individual itself? 
Would not a wild duck if it were obliged to walk during 
all its life from its coming out of the egg acquire a similar 
hypertrophy of these bones? Unfortunately we have not 
exact measurements on this point which alone could de- 
cide the question whether hypertrophy acquired during 
the life of an individual could attain the same degree as 
that which has been observed in the domestic duck. 
Several travellers have remarked that when men have 
127Darwin: The Variation of Animals and Plants under Vol. IT. 
P. 367. 
