THE SCOPE OF ZOOLOGY 



complex and extensive that he could not begin to solve it in a lifetime of 

 hard work. The simplest kinds of problems have a way of becoming 

 difficult and complex when investigation starts ; and, if there is to be any 

 hope of success, it is well to be quite conservative when selecting a prob- 

 lem for study. As an example, an eager but untrained investigator 

 might select the method of human inheritance as a problem. Hundreds 

 of investigators working on many different phases of this problem for 

 many years have not been able to get a complete solution. Hence, it 

 would be much better to select a much smaller field of investigation. 

 For instance, the method of inheritance of harelip in man would be a 

 problem that would require extensive study, but with a good chance of 

 a satisfactory solution. Even with this comparatively simple and nar- 

 row problem, however, there might be complex ramifications that would 

 require years to untangle. 



After a problem has been formulated, the next step in the scientific 

 method is the formulation of an hypothesis. This is a postulation or a 

 good guess as to a possible solution to the problem. It will be easier to 

 find the correct solution if there is some possible explanation to test out 

 in the investigations. In order to make a reasonable hypothesis, it is 

 necessary for the investigator to survey all of the scientific literature in 

 the field and to find out what has been done by others that might throw 

 light on the problem. He may even find that someone else has already 

 solved the problem and that he would have to select another problem. 

 At anv rate, he would save himself the time and trouble of repeating 

 extensive investigations already done by others. In the case of inheri- 

 tance of harelip, let us assume that the method of transmission of this 

 defect has not been worked out definitely, but the information gathered 

 on the subject indicates that harelip might be inherited as a dominant 

 characteristic. Such a characteristic shows in persons who receive the 

 hereditary factor for it from either parent. Accordingly, a hypothesis 

 is formulated to the effect that harelip is inherited as a dominant 

 characteristic. 



Once a working hypothesis has been formulated, the scientist may 

 then set himself to work to test the hypothesis against facts. Observa- 

 tion and experimentation may be used for this purpose. In some cases 

 observation will be the primary method of investigation. For instance, 

 in a study of the inheritance of harelip in man we would be limited to 

 observation because we cannot conduct experiments in breeding human 

 beings in order to determine methods of inheritance of certain charac- 

 teristics. It would be possible, however, to study families in which 

 harelip has occurred and to note the relationships of the afflicted persons. 

 By tabulation and analysis of the results of a large number of such 



