O GEOLOGICAL BIOLOGY. 



whole, to look at organisms as related to each other in the com- 

 plex environment of the earth, the temporary world-surface, 

 and in the consecutive time-relations which are recorded in the 

 geological strata making up the surface of the globe. In the 

 life-history of the individual, or Embryology, we have the 

 body of the individual to bind together the various stages of 

 development. For this history the hours of the clock or 

 the days of the calendar are satisfactory time-divisions. The 

 relations of the various organs or parts to each other are 

 easily determined by noting the effect of artificial separation 

 or excision ; but we see no history of organisms until we 

 compare those now living with others that lived unmeasured 

 hours and days and even years ago. Comparison of living 

 species with living species only, shows us differences which 

 our classifications enumerate. While we might, theoretically, 

 guess that the present living organisms came from others not 

 like them, if we knew nothing of fossils this would be but a 

 mere vague fancy, and could never find a place in true sci- 

 ence. Paleontology, however, reveals to us a long series of 

 organic forms, and when we speak of their history we assume 

 that the series is connected genetically ; the time-relations we 

 read from the rocks, and in terms of subjacent strata. The 

 relationship must be determined by comparison of entirely 

 distinct forms ; we must learn of organisms from their fossilized 

 remains. These and many other facts must be presented 

 before we have the data for defining the successive steps of 

 the history. 



Organisms and Environment. — Our subject, then, divides 

 itself into two grand divisions, organisms on the one hand, 

 and, to use a very comprehensive term, enviroiinieiit on the 

 other hand — living things, and the conditions under which 

 they have lived. The environment or conditions of life are 

 strictly included in the science of Geology, — for geography is 

 but the present final product of geological processes. When 

 we treat of Biology geologically and study the history of 

 organisms, we assume the truth of two propositions which 

 are not required in the study of the characters and the devel- 

 opment of the individual organism. The propositions are : 

 first, that long periods of time have elapsed separating the 



