58 ELEMENTARY ZOOLOGY. 



In any experiment the following steps should be taken : 



1. State in writing just what you wish to determine. 



2. State the steps you propose to take in getting your 

 information, and why you take each. 



3. State your observed results simply as matters of 

 fact, without any reference to the conclusions to 

 be drawn from them. 



4. Make the inferences that you think are supported 

 by your facts. 



a. Sensitiveness. (Much interesting work may be done 

 in respect to sensitiveness. If time allows, it is excel- 

 lent exercise to devise original experiments in order 

 to test the presence or absence of a given sense.) 

 See if you can get them to feed by placing the edge 

 of a leaf close to the mouth of a specimen that has 

 not eaten recently. Afterward dip the edge of the 

 blade of grass in a salt solution and note the results. 

 Does he recognize any difference? Evidences? Try 

 another specimen with another blade of grass dipped 

 in a solution of quinine. Note and interpret results. 

 Try still other materials. 



Devise experiments to test whether they are sensi- 

 tive to odors. If so, where is the sense located? 

 Evidences. 



Are you sure they are sensitive to light? How many 

 proofs of your conclusion can you advance ? Can they 

 distinguish colors at all ? How can this be determined ? 

 Are you sure that your experiment really tests it? 

 Do the two eyes cover wholly different fields? Is 

 there any part of the field that the animal cannot 

 see without changing position? Evidences. 

 Similarly, devise experiments to determine -whether 



