THE BEGINNINGS OF LIFE. 75 



marily recognized by this process. The tree that puts 

 out leaves when the spring brings change of tempera- 

 ture, the flower which opens and closes with the rising 

 and setting of the sun, the plant that droops when 

 the soil is dry and re-erects itself when watered, are 

 considered alive because of these induced changes j in 

 common with the zoophyte which contracts on the 

 passing of a cloud over the sun, the worm that comes 

 to the surface when the ground is continuously shaken, 

 and the hedgehog which rolls itself up when attacked.' 

 And, not only do we expect some response when a 

 living organism is acted upon by a stimulus, but there 

 is a sort of fitness in the response, different from the 

 reaction of mere dead matter under certain changes 

 of condition. In the latter c the changes have no 

 apparent relation to future external events which are 

 sure or likely to take place,' whilst in the former the 

 vital changes manifestly have such relations. Then 

 too, as Mr. Spencer says, familiarity with the fact must 

 not allow us to overlook the significance of the con- 

 sideration, c that there is invariably, and necessarily, 

 a conformity between the vital functions of any 

 organism, and the conditions in which it is placed 

 between the processes going on inside of it, and 

 the processes going on outside of it. We know 

 that a fish cannot live in air, or a man in water. 

 An oak growing in the ocean, and a sea-weed on 

 the top of a hill, are incredible combinations of 

 ideas. We find that every animal is limited to a 



