But by what law of "natural selection," appertaining to a single pair of old world monkeys, have their offspring advanced to this regal state of manhood, while all other pairs have remained stationary, or precisely where they were two hundred and fifty thousand years ago or more? Why this exceptional divergence in the case of a single pair of monkeys? Why this anomalous, aberrant, and thoroughly eccentric movement on the part of nature? We had supposed that her operations were uniform--conformable to fixed laws of movement. The doctrine of the "survival of the fittest" implies this. Why then, should nature, in her unerring operations, have selected the fittest in respect to a single pair of Catarrhine monkeys, and at the same time rejected the fittest in the case of a million other pairs? If she had selected only the fittest in respect to this old world stock of monkeys, the entire Catarrhine family should have disappeared in the next higher or fitter group--a group nowhere to be found in geological distribution. The break between man and this Catarrhine monkey covers quite a series of links in the genetic vinculum;[37] and yet between the two we find no high form of a low type fitting into a low form of a high type, as we manifestly should, to account for all the diversified changes that must have taken place in the interim. And what is true of the types is measurably true of the classes within the types, as well as of the orders within the classes. Wide deviations in forms, as in characteristics, would seem to be the invariable rule; the blending of type into type, except perhaps in remote relationships, is nowhere visible.