ADDRESS OF THE PRESIDENT. 59 



A new thought, however, was in process of formation which was destined 

 to attract much attention and arouse the thinkers of the world and that was 

 the theory of evolution. 



Darwin's Origin of Species set the world in a whirl of thought. For half 

 a century this thought has been advanced by one school of thinkers and hotly 

 contested by another. Battle after battle has been waged and compromise 

 after compromise has been made, and now at the close of the century has this 

 tliought come to be recognized as of inestimable value in lli(> interpretation 

 of the great book of nature. 



James Dana took up this new thought and made use of it in his geological 

 studies. He thought of the development of the earth as a unit. Geology was 

 not simply a record of geological events but a study of causes and effects — 

 a real philosophic study. Under his skillful research and thinking Geologj^ 

 was rapidly organized into a real science. Explanation of the origin of ocean 

 })asins and continents, the mountains and valleys, the stratified aiul unstrati- 

 fied rocks, the water and the heat, the great variety of organic forms and the 

 origin of the earth, now could be more satisfactorily interpreted. The age o," 

 tile earth, the mineral resources, and their uses to man, the evolution of the 

 various forms of life, and the origin of man have received the most thorout^h 

 attention on the part of the greatest geological thinkers of the world. 



V. Biology. 



The last line of scientific thought that will engage our attention is biological. 

 This is the most important for it deals with life problems and these concern 

 us most acutely. This science was also born in this century. While many 

 facts were known concerning plants and animals yet the prijiciples underlying 

 the life of these organisms was little understood. 



The first valuable work of the century was in the realm of embryology. 

 The greatest work was done by VonBaer. He began his inv(>stigations in 

 1819 after reading the works of Pander. After many years of study he estab- 

 lished the truth of the three germ layers, and the development of the various 

 tissues and organs from these layers. This gaA^e a new direction to the study 

 of embryology. Balfour, Huxley, Remak, Hertwig, and others continued 

 these studies and brought the subject to its present stage. In these investi- 

 gations a new line of thought has been evolved, that of cell-lineage. Boveri, 

 Conklin, Wilson, Whitman, Lillie, and others have shown that there are 

 certain areas in the protoplasm of the egg that give rise to definite parts' of 

 the adult animal. 



The next great truth to be discovered was that set forth in the cell theory, 

 that all i)lants and animals are made of cells. In 16(35, Robert Hooke of 

 England observed the cellular structure of cork and spoke of the little 

 boxes composing it, but he did not realize the full purpose and nature of 

 these. It was left to the jjresent century to fully establish and announce 

 this tlieory to the woi'ld. This honor belongs to Schleiden and Schwaim 



