164 THE PATH OF SCIENCE 



fensible to make detailed studies o£ structure and function 

 while neglecting the environmental factors in response to 

 which the structure and function evolved, but ecology is only 

 now coming into its own. Old-fashioned natural history is 

 becoming strictly scientific. The habitats of organisms are 

 coming to be described not in vague terms, but in the form 

 of accurate numerical data for the temperature and humidity 

 of the atmosphere, the intensity of the visible and ultraviolet 

 light, and so forth. The complex interrelations of organisms 

 are also beinsr disentans^led. It has been shown that there 

 are regular cycles in the abundance and scarcity of many 

 species, though we do not yet understand the underlying 

 causes. It is very unfortunate that ecological studies have 

 come so late in history; for man has acted like a vandal in 

 destroying the natural habitats in which organisms evolved. 

 In Great Britain only a few small patches of virgin country 

 remain. Through his radical transformation of his own habi- 

 tat, man has disturbed that of most terrestrial organisms. He 

 himself has become an environmental factor in the lives of 

 plants and animals comparable in importance with the nat- 

 ural phenomena of temperature, humidity, mountain-build- 

 ing, and the rest. It is a pity that he did not start studying 

 ecology before he nearly destroyed the natural subject matter 

 of this branch of biology. The ecology of the future is likely 

 to be concerned mostly with the relationships of organisms 

 to the artificial environments created by man. 



The grand period of biology started and ended with cyto- 

 logical studies. The year 1838 saw the formulation of the 

 cell theory. About half a century later the general principles 

 of chromosome behavior were known. Now, at last, a retro- 

 gressive movement had set in. Darwin's theory led to a con- 

 centration of attention on the structure of organisms with a 

 concomitant loss of interest in their substance and functions. 

 People who could have been continuing the scientific study 

 of organisms were indulging in speculation and drawing dia- 

 grams from their imagination showing ho^v one group of 

 organisms had been derived from another. A book was writ- 



