Slow and insensible changes of this kind could never be recognised unless actual measurements or careful drawings of the breeds in question have been made long ago, which may serve for comparison.
In some cases, however, unchanged, or but little changed, individuals of the same breed exist in less civilised districts, where the breed has been less improved.
There is reason to believe that King Charles' spaniel has been unconsciously modified to a large extent since the time of that monarch.