38 



WHAT IS BEING ALIVE? 



plants or animals. Adaptability is also a characteristic of living 

 things. We say that a plant or animal adapts itself to its sur- 

 roundings, meaning that some structure of the animal or plant 

 has made it possible for the organism to live under the conditions 

 in which it is placed. 



A little over two hundred years ago, a Dutchman, Anton van 

 Leeuwenhoek (la'ven-hdok), became interested in lenses. He 



observer 



Culver Service 



Anton van Leeuwenhoek was at first 

 only interested in grinding lenses and mak- 

 ing crude microscopes so that he could 

 see things Digger than the naked eye 

 could see them. But later he became in- 

 terested in observing minute animals that 

 could not be seen with the naked eye. 

 Through his discoveries and observation, 

 incentive was given to the study of bac- 

 teria. 



ground hundreds of them, and used them in various combinations 

 to magnify tiny plants and animals. With these improved lenses 

 he was able to see tiny organisms swimming in drops of pond water, 

 and it is even thought that he probably saw living bacteria. An 

 English doctor, Robert Hooke (1635-1703), examined a small section 

 of Cork, which is the bark of an oak tree, and found it was made up 

 of tiny compartments, like rooms, which he called cells, a term which 

 is now universally used for the unit of structure in living things. 



