CHAPTER 



4 



Measurements 



Classical or descriptive biology has developed a tremendous vocabulary 

 for describing various aspects of organisms. Even a description of an 

 organ of a plant or animal, however, must eventually depend upon some 

 quantitative measurement. The fact that the tip of a leaf is more-or-less 

 rounded is frequently less important than some estimate of the over-all 

 size of the leaf. 



Experimentation in biology certainly could not function except in 

 a quantitative manner. If materials are produced by cells they are pro- 

 duced in some quantity. If a part of an animal moves, it moves some 

 distance. If some environmental factor is important in the behavior of 

 an animal, the intensity of that environmental factor may have a pro- 

 found influence. It is almost impossible to imagine experimentation in 

 biology that did not depend upon measurement. In this respect we are 

 completely dependent upon methods developed by the physical scien- 

 tist. 



Standards 



Any measurement is a comparison of one thing with another. If we 

 compare A with B and then later compare A with C, the information 

 gained can be used to compare B with C. In this simple case A becomes 

 a form of standard. Modern measurement uses a set of standards which 

 have been selected by mutual agreement. The importance of the stand- 

 ards in science and in commerce should be obvious. 



30 



