Ill 



THE TROPISMS AND THEIR RELATION TO MORE 

 COMPLEX MODES OF BEHAVIOR 



■T^HE subject of animal behavior has been of in- 

 -'- terest to human beings from the earliest times, 

 but it has not been taken very seriously until a com- 

 paratively recent date. The ways of animals were 

 considered curious, interesting and in many ways use- 

 ful things to know about, but the great theoretical 

 import of animal psychology was unsuspected until 

 it came to be recognized that our own minds are 

 the outgrowth of the animal mind, and that to obtain 

 a truly scientific human psychology it is necessary to 

 have a clear insight into the psychology of the lower 

 animals from which we are descended. Near the 

 middle of the nineteenth century Herbert Spencer 

 enunciated the principle that, "If the doctrine of evo- 

 lution be true the inevitable implication is that mind 

 can be understood only by observing how mind is 

 evolved," and he boldly plunged forward upon an 

 undertaking to remodel the science of psychology 

 from the genetic standpoint. The result was the 

 publication in 1855, four years before the appear- 

 ance of the Origin of Species, of the Principles of 

 Psychology, a work which for sheer originality, inde- 

 pendence of treatment and profound grasp of the 



50 



