as the individual, he might perhaps have been led to conclusions which are as true as they are surprising.
Taking into account this attitude of the general public, and in particular that of the mass of medical men, to whom, if to any, this work should prove of interest, and considering also that a wide audience must be appealed to if it is to have that amount of practical usefulness which the author hopes for it, it seems needful, before proceeding with the main body of the work, to set forth as briefly and clearly as possible certain biological data on which the argument is founded; especially as, so far as the author is aware, they have never yet been explained in sufficiently simple terms to be comprehensible by the general reader; and more especially since, in his conception of the process of evolution, the author differs somewhat from accepted views, or rather since in his opinion acknowledged authorities have not recognized or have not laid sufficient stress on certain processes of evolution which appear to him of the greatest importance. This book is therefore divisible into two parts: in the first the problem of evolution in general is very briefly dealt with, but an attempt is made to penetrate somewhat deeper in certain directions than has hitherto been done; in the second part, the conclusions arrived at in the first are applied to the problem of man's present evolution, and an endeavour is made to show that this evolution is proceeding in a direction hitherto altogether unsuspected.
To many, and, surprising as it may seem, even to some medical men, in spite of what ought to be a scientific training, the theory of evolution means nothing more than the theory of the descent of man from the monkey. In reality it means much more; it teaches that plant and animal types have not persisted unchanged from the time life first became possible on the
