Important Events 17 



our knowledge of water life. Chiefly as a result of their 

 labor there emerged out of this ancient "natural 

 philosophy" the segregated sciences of zoology and 

 botany. Our modern conceptions of biology came 

 later, being based on knowledge which only the per- 

 fected microscope could reveal. 



A long period of pioneer exploration resulted in the 

 discovery of new forms of aquatic life in amazing 

 richness and variety. These had to be studied and 

 classified, segregated into groups and monographed, 

 and this great survey work occupied the talents of 

 many gifted botanists and zoologists through two 

 succeeding centuries — indeed it is not yet completed. 

 But about two centuries after the construction of the 

 first microscope, occurred an event of a very different 

 kind, that was destined to exert a profound influence 

 throughout the whole range of biology. This was the 

 publication of Darwin's Origin of Species. This book 

 furnished also a tool, but of another sort — a tool of the 

 mind. It set forth a theory of evolution, and offered 

 an explanation of a possible method by which evolution 

 might come to pass, and backed the explanation with 

 such abundant and convincing evidence that the 

 theory could no longer be ignored or scoffed out of 

 court. It had to be studied. The idea of evolution 

 carried with it a new conception of the life of the world. 

 If true it was vastly important. Where should the 

 evidence for proof or refutation be found? Naturally, 

 the simpler organisms, of possible ancestral character- 

 istics, were sought out and studied, and these live in the 

 water. Also the simpler developmental processes, with 

 all they offer of evidence; and these are found in the 

 water. Hence the study of water life, especially with 

 regard to structure and development, received a mighty 

 impetus from the publication of this epoch-making book. 

 The half century that has since elapsed has been one of 

 unparalleled activity in these fields. 



