152 Sioux City Academy of Science and Letters. 



made, it would last, it would endure for an equally long 

 time. That this plant changed twice within a few years 

 in response to changed surroundings is ample proof to 

 convince me that it would also change as much or more 

 under a natural change of environment, and that the 

 change would be permanent while its surroundings were 

 unchanged. 



Nature also provides for natural selection and sur- 

 vival of the fittest in another way. That is, by the birth 

 of far more organisms than can ]3ossibly survive to ma- 

 turity and the age of reproduction. Because of this there 

 comes about a struggle for existence between the mem- 

 bers of the same species, in wliich those individuals who 

 may possess any suj)eriority over their fellows have a 

 better chance to live and transmit their superiority to 

 their descendents. Among animals, the elephant is the 

 slowest breeder known, and yet, in the short time of 

 seven hundred and fifty years, if all the progeny of a 

 single pair should survive to maturity, there would be 

 nearly nineteen million living elephants. Man doubles 

 his numbers in about twenty-five j^ears, and, if all had 

 reached maturity, their descendents would fill all the 

 earth as thickl}^ as they could stand in less than ten cen- 

 turies. Natural selection has been a continually acting 

 force during all the ages of the past, by which the whole 

 organic world has been developed by a choosing of those 

 beings which were nearest in harmony with an ever- 

 changing environment. 



Now let us see if we can trace the course of this 

 development, both in plant and animal forms. What 

 does a study of the myriad forms of ancient life, pre- 

 served in the rocky leaves of the book of nature, teach 

 us of the condition of the inorganic world at the time in 

 which they lived? If we go into a museum where are 

 gathered together specimens of the handiwork of man 

 for many centuries of the past, we can tell at once what 

 was the civilization of the people whose work we are 

 studying. From the works of man in the highest cul- 

 tured nations of the x)resent time, back to the relics of 

 man in the rough stone age, there is a long line of speci- 

 mens that gradually become less beautiful in design, fin- 

 ish and esthetic use, until we reach the rough stone im- 



