254 



GENERAL BIOLOGY 



improvement in capacity for sustained, speedy and well 



directed flight, as 



f "^ "^ ^-^==-=* 5r ^, the reduction of re- 



dundant, and the 

 readjustment of the 

 remaining veins 

 proceeds. It is a 

 sign of a generalized 

 condition when 

 many parts of an 

 organism are found 

 similar 

 The 



FIG. 157. Beard tongue (Pentstemon pubescens). 

 a, a flower viewed from the side; b, the same 

 with the side of the corolla cut away, showing 

 the elongated, declined and hairy fifth stamen ; 

 arrow indicates the path of the entering bee. 



performing 

 functions. 



earthworm is very 

 generalized in the almost unending repetition of like parts 

 in successive segments. The malacostracan Mysis (fig. is6a) 



FIG. 158. Mysis stenolepsis (after Paulmier). 

 b, ' A mud crab. (Panop;eus depressus). 



