BIOLOGY AND PROGRESS 219 



night. The acuteness of hearing in dogs has been 

 a source of wonder for a long time and their 

 ability to follow a trail by scent is truly marvelous 

 when compared with man's degenerating sense of 

 smell. 



Although man's sense organs do not equal those 

 of some of the animals, they are all that he has 

 and when supplemented by mechanical devices, en- 

 able him to become aware of more facts in his 

 environment than can any animal. 



In so far as students have been able to deter- 

 mine, men's sense organs are stimulated in just 

 the same manner as the sense organs in a dog, 

 snake or fish. There has been no discovery that 

 permits us to place man in a class by himself in 

 this particular. 



These obvious facts long ago stimulated men 

 to seek for some other structure that would ac- 

 count for the marked difference between them- 

 selves and the animals and so they have devoted 

 much time to analyzing his cerebral hemispheres 

 which are so conspicuous for their size. To this 

 part of the brain all of the sense organs eventually 

 report and they also have just the same relation 

 in the dog or monkey. But it was early evident 

 that man possessed more complex cerebral hemi- 

 spheres than any animal but thus far this com- 

 plexity is the chief structural difference that has 

 been discovered. 



