176 INSECTS, AND THEIR RELATION TO MAN 



i. Making a Logical Definition 



Observations, 1. Make a table of resemblances of the 

 preceding seven orders of Insects, using the following form : 



2. What characters in the above table fit all the insects 

 studied ? Write them out into a definition of an insect (class 

 Insectd). 



Note. Orders which are alike form a class. While our 

 definition just formed is not complete, yet it illustrates how 

 logical definitions are made. 



Conclusions. 1 . What is an insect ? Note. There are 

 some 400,000 kinds of insects already known. 1 Each kind, as 

 of grasshoppers, is called a species. So a species is made 

 up of individuals that are very much alike. Species that are 

 very much alike form a genus. Genera that are much alike 

 constitute a family and families much alike constitute an 

 order, as the Order Orthoptera. As with a man, every animal 

 and plant is given two names. Thus the typhoid fly is 

 named Musca domestica, which is a combination of the generic 

 name first, followed by the specific name, much as a man's 



1 More than all other known kinds of animals taken together. 



