BIOLOGICAL PHILOSOPHY 4OI 



sound are expressions of movement, and the electronic theory of matter 

 postulates that matter itself is a cosmos of ceaseless energy. But the vitalist 

 tells us that living matter possesses "spontaneity," which is lacking in the 

 non-living world. The living thing moves of its own "volition," the non- 

 living only under the influence of forces external to itself. But what evi- 

 dence have we of "volition" on the part of an Amoeba or a bacterium, 

 while the energy of the living machine is as truly the result of oxidation 

 of fuel as is that of the steam turbine or the automobile. Any distinction 

 then on the basis of motion alone between the world of the living and the 

 non-living is a fallacy. 



Adaptation is one of the characteristic features of life. The bird and bat 

 are adapted for flight, the fish for swimming, the monkey for climbing: 

 one need not enumerate, for one cannot name a single living thing which 

 is not adapted to the conditions of its existence: otherwise it would not 

 exist. 



But are living things alone adapted to their environment? Does not the 

 river adapt itself to its channel, the lake to its basin, and the gas to the form 

 and size of its container? Ice exists in winter because it is adapted to the 

 cold and disappears in summer because it is not adapted to the heat. Adapta- 

 tion indeed is merely an expression of action and reaction, of cause and 

 effect. The fact of adaptation in the inorganic world remains however 

 and when the riddles of life have been solved it is not unlikely that the 

 process of adaptation of living things can be resolved into simple physico- 

 mechanical terms, just as surely as can the adjustment of the river to its 

 channel or the snow drift to the wind. 



Yet another manifestation of life is its irritability or power of response 

 to stimuli. Examples of this are so common that it is merely trite to repeat 

 them. But is this phenomenon limited to life alone? Does not lifeless matter 

 also respond to stimuli, or changes in its environment? Examples of such 

 changes must occur to the mind of everyone — changes in volume or in 

 state, whether solid, liquid or gaseous, in response to changes in tempera- 

 ture or pressure, are among the most famihar instances of these responses. 

 If a metal is heated, its electrical conductivity is decreased, sound travels 

 faster the higher the temperature, while atmospheric conditions will mate- 

 rially affect the messages of the radio. While the responses of living things 

 and changes in their environment are infinitely more complex and indirect 

 than those of the non-living, yet the same principle holds true for both. 



Yet one great characteristic of life remains, namely, reproduction. The 

 development of a human being with his myriad cells, more varied in form 

 than the manifold parts of the most complicated machine, ranging in size 

 from the tiny corpuscles of the blood, less than one four-thousandth of an 

 inch in size, to the motor nerve cells of the spinal cord, which may reach 

 a length of over three feet; and including the intricate structures of the 

 brain by which are performed all the wonderfully complex»functions of the 



