Biologists Study Anivials and Plmts 



Fig. 7 A corner of the Boy 

 Scout Museum at Bear 

 Mountain, New York. What 

 suggestiotis for hobbies does 

 this picture give you? 



(AMERICAN MUSEUM OF NAT- 

 URAL history) 



scientist. The well-equipped workshop 

 has sinks with faucets of different sizes; 

 stone tables with vacuum and air pres- 

 sure outlets and connections for gas 

 and electricity; rows of shelves for bot- 

 tles of dyes, acids, testing agents, glass- 

 ware of many kinds, and some reference 

 books; cupboards with microscopes, 

 dissectingr instruments and other instru- 

 ments of various sorts. There may be an 

 incubator, a pressure cooker, a refrig- 

 erator. The laboratory is the place in 

 which biologists perform their "labors," 

 in which they investigate, observe, ex- 

 periment, draw conclusions, and record 

 their studies of living things. That is 

 why boys and girls who set up little 

 places at home for the study of living 

 things may speak of them as biologists' 

 workshops or laboratories. 



A peep into a laboratory. The great 

 Russian biologist, Ivan Pavlov ( 1 849- 



1936), in the early years of the present 

 century wished to learn something of 

 animal behavior. Let us visit him in his 

 laboratory. He used dogs as experimental 

 animals because they M^ere easy to work 

 with. Pavlov wanted to find out how 

 the saliva can be made to flow in a dog. 

 But before he could begin his experiment 

 he had to perform a difficult operation. 

 He opened a small hole in the dog's 

 face and inserted a tube to which a jar 

 was attached. When Pavlov showed 

 food to the dog, the saliva flowed into 

 the jar and the amount could be 

 measured. It took weeks to train the 

 do^- to stand still in a harness while he 

 was fed. After these preparations Pavlov 

 was ready for his experiment. He rang a 

 bell each time he put food before the 

 doer. This was continued for some time. 

 Then, one day, Pavlov rang the bell 

 without putting the food before the 



