324 THE BIOLOGY OF INSECTS 



that biology is not an ** exact " science, it is a limitation that 

 must be accepted when the subject under consideration is 

 life as shown in some of its almost infinitely varied mani- 

 festations. Our classificator\^ scheme, because of its un- 

 certainty- and difficulty, becomes a natural introduction to 

 the problems of interpretation which are to be discussed in 

 the follo\N^g chapter. 



