74 Sioux City Academy of Science and Letters. 



claimed for himself the center of the universe, with sun, 

 moon and stars created for his special benefit, wheeling 

 around the earth as a center. Today we know more of 

 nature's laws, and have learned that man, while the last 

 and highest product of evolution, is only one of the al- 

 most infinite number of organized beings that have had 

 their home on this earth, itself only a tiny speck among 

 the myriads of other like bodies filling the space of the 

 cosmos. There is absolutely no arbitrary line, either 

 mentally or physically, dividing man from the other or- 

 ganized beings sharing with us a home on this earth. 

 As we know that the physical body has been developed 

 from the lowest unicellular organisms up to man, so we 

 believe that the mental life has been slowly unfolded 

 and developed from moner to man, moving forward and 

 upward along with the physical development of the nerv- 

 ous system of the body. It is much easier to trace stej) 

 by step the evolutionary development of the mind than 

 it is that of the body. There are no "missing links" in 

 mental development as there are in bodily evolution. 

 All the graduations of mind are with us, while to follow 

 the evolution of body we must rely largely on paleon- 

 tology, going back millions of years into the past seeking 

 for the lost links of the bodily changes. 



During the Tertiary age, the physical development 

 of animal life reached its limit in size of body. There 

 were giants in those days. Animals gigantic in bulk 

 swarmed in the waters and roamed through the forests 

 in their search for food. But with their overgrown 

 bodies they could not change with the ever-changing en- 

 vironment, and in their struggle for existence they fell 

 by the wayside and perished. A study of their fossil 

 remains teaches us that they were small in brain, slug- 

 gish in movement, and generally plant-eating animals. 

 The brain cavities in the skulls of these animals were 

 remarkable for their diminutive size in comparison to 

 their bulk in body. From their extinction development 

 in size of brain took the place of bodily development, 

 and in this increase of brain capacity was the first pos- 

 sibility of man with his ever-growing mind and intellect. 

 Only within a few years has the study of the brain been 



