Febkuaey 18, 1910] 



SCIENCE 



251 



to have an essential relation to climate, but 

 at present I believe we can not fairly say 

 that that relation has been shown to have 

 existed. On the other hand, there appears 

 to be a definite connection between the 

 physical geography of the earth's surface 

 and the climate of any corresponding 

 epoch. Large continents and high lands 

 have been associated with diversity of 

 climate; small continents or archipelagoes 

 and low lands have been associated with 

 uniformly genial climates. Moreover, the 

 chemical reactions between rock masses ex- 

 posed to weathering and the critical con- 

 stituents of the atmosphere and the seas, 

 such as carbonic acid and moisture, appear 

 to establish a chain of phenomena, which 

 involve temperature and humidity, and 

 which affect the intensity of provincial 

 climatic differences. In a broad and gen- 

 eral sense we may refer to the periodicity 

 of climatic change in the same way that we 

 recognize periodicity of general diastro- 

 phism, and the cycles of the one appear to 

 coincide with the cycles of the other. 

 Chamberlin has recognized the relation 

 and has endeavored to trace it through the 

 critical influence of the small percentage of 

 carbonic acid in the atmosphere. In fol- 

 lowing the course of that critical element 

 from the air through the laboratory of the 

 lands and seas back to the atmosphere, he 

 established a chain of phenomena which is 

 unquestionably a vera causa of the common 

 periodicity of the phenomena. 



We may conclude then that the study of 

 ancient climates involves two connected 

 problems. The first relates to the distribu- 

 tion of provincial climates according to the 

 distribution of lands, seas and permanent 

 oceans. It may be approached by applying 

 the laws of modem meteorology to a pre- 

 liminary solution. That solution must, 

 however, be tested against the geologic and 

 paleontologic evidence of the corresponding 



time, and must be qualified by conclusions 

 based upon broader principles which in- 

 volve the physics and chemistry of the at- 

 mosphere in its relations to land and sea. 

 Through these the second problem, which 

 involves the periodicity of climates, is to 

 be approached. 



EVOLUTION AND ENVIRONMENT 



In the long chain of causes and effects 

 initiated by terrestrial and solar energy, 

 the development of life is the latest link. All 

 that precedes life is characterized by 

 change which moves in a series of cycles. 

 Life, on the other hand, is characterized 

 by change which has moved forward in 

 progressive evolution. Upon this funda- 

 mental distinction we separate the inor- 

 ganic from the organic and recognize the 

 latter as pertaining to a higher phase of 

 development. 



Evolution is not, however, the only attri- 

 bute which distinguishes life from the 

 lifeless, for life is qualified by the further 

 attribute of death. The individual, the 

 species, the genus, the family and race, 

 everything Avhich lives, ultimately comes to 

 the final end, and there is in the evolution 

 of the organic no return of that which has 

 thus died. While the inorganic world re- 

 peats, the organic world never does. 



Profound as these distinctions are, they 

 nevertheless do not emancipate the organic 

 from the control of the inorganic. Life is 

 inexorably conditioned by its environment. 

 Through ages of evolution and adaptation, 

 each individual is fitted to exist under a 

 special set of circumstances which consti- 

 tute his environment. Narrow limits are 

 set to the capacity of the organism to ad- 

 just itself to sudden changes, and only 

 within those limits can it continue to exist. 

 Beyond them on all hands stands the in- 

 evitable death. In the history of the in- 

 dividual there are special periods of 



