INTRODUCTION 9 
of evolution in general is perfection of adaptation to the conditions of 
life as they happen to be at any particular time. Many a highly 
perfected creature has reached the goal of its evolutionary course 
only to perish because it was too highly perfected for a particular 
environment and could not withstand the hardships incident to radi- 
cally changed world-conditions. Many evolutions therefore have 
been completed, while others are still awaiting the opportunity to 
speed up toward a new goal. 
7. Evolution is therefore not entirely a thing of the past. Obvi- 
ously some species, including Man perhaps, are nearly at the end 
of their physical evolution, but there are always certain generalized 
plastic types awaiting the next great opportunity for adaptive speciali- 
zation.—Eb.] 
