THE MICROSCOPE IN ZOOLOGY. 



75 



Plant Lice. 



been a question how the fly and other insects can 

 maintain their position in an inverted attitude. The 

 foot, or tarsus, of the fly consists of five pieces, " the 

 first of which contains a pair of muscles which move 

 the second upon it, but the remaining four contain 

 none," The last joint has a pair of pads (pulvillt)^ 



