248 THE RING OF NATURE 



then inserted his tooth in the faint crack that he 

 had uncovered, and jerked the two shells apart. 

 But make certain that it was indeed the squirrel 

 that did this, for because it is the best known way 

 of opening a nut, man has copied it and opens his 

 nuts with a jack knife in the very same way. It 

 is easy to see whether the opening has been effected 

 with the curved instrument of the squirrel or with 

 the straight edge of the jack knife. 



