90 TAXONOMY. 



Importance of Confirming Result* Obtained in the 

 Study of One Organ by the Study of Other Organs. 



A classification based upon the study of a single 

 organ must be considered provisional. 



Illustration drawn from tbe Saturniidaf. 



Different results obtained from a study of the an- 

 tennae, and from a study of the radius of the fore wings 

 of the SaturniidiK. 



Conclusion that while, as a rule, the tendency of nat- 

 ural selection is towards a reduction in the area of the 

 wings, thus fitting them for more rapid flight, a condi- 

 tion may arise, as a high specialization of an organ of 

 special sense (presumably an organ of smell), in which 

 a soaring flight is more desirable. Under these cir- 

 cumstances selection will tend to widen the wings. 



