THE SCOPE OF ZOOLOGY 



11 



combine food and oxygen to release energy outside of a living cell 

 through the process of combustion, but this is a very rapid release of 

 the energy as heat. In the cell the same amount of heat will be re- 

 leased, but it is released much more slowly — otherwise the cells would 

 become overheated. 



4. Response to Environment. All living things respond to their 

 environment in a manner which is usually advantageous to themselves. 

 This is sometimes known as irritability. The response may be quick 



Photo by Winchester 



Fig. 1.2. Mixed-up bird? It might appear as if the eyes of this owl have gotten 

 mixed-up in their adaptations to light, but actually this is an excellent illustration of 

 the short-term adaptations of living things. The picture was made by flash in a dark 

 room while a flashlight was shining into the left eye of the owl. Thus, the left eye 

 is adapted to a bright light, but the right eye is adjusted to the darkness of the room. 



and fleeting or it may be longer in developing and longer persisting. 

 If you touch a hot stove with your finger, your response is quick and 

 definitely advantageous to yourself. This is a short-term adaptation 

 to a temporary environmental condition — a quick stimulus-response re- 

 action. If you go into a darkened room from bright sunlight you will 

 temporarily be unable to see, but within several minutes the irises of 

 your eyes will open up and admit more light. Plants turn their leaves 

 in such a manner that they receive the best exposure to sunlight. Non- 



