3 2 



GENERAL BIOLOGY 



insects would not be large enough, and weaker ones would 



not be strong enough to swing 

 open the heavy doors of the 

 pollen cupboard: so this flower 

 reserves its pollen as well as its 

 nectar for its special guests 

 and affords 

 of mutual 

 siveness. 



us a good example 

 fitness and exclu- 



FIG. 24. Diagrams illustrating 

 the structure of the ordinary 

 flower of the violet (Viola 

 cucullata). a, a front view 

 of the flower with the tip of 

 the saccate petal cut away, 

 showing the blockade of 

 hairs around and above the 

 stigma; b, lateral view with 

 petals and sepals in part re- 

 moved ; c, the same more en- 

 larged, and with the lateral 

 stamens removed ; d, one of 

 the spurred stamens; drop- 

 lets of nectar on its outer 

 side shown at o, and pollen 

 cavities, at p. 



Study 5. A case of precise 

 adaptation. 



This is an individual study, to 

 be undertaken only when condi- 

 tions are right proper flowers 

 abundant, warm and sunshiny 

 weather, etc. A highly special- 

 ized flower with its nectar not 

 easily accessible to flower visitors 

 should be selected, and it should 

 abound in freshly blooming 

 clumps ; for the visits to such flow- 

 ers are often few and far between. 



The Record of this study may 

 well consist of a few drawings to 

 illustrate the structure of the 

 flower and the details of the en- 

 trance, of the feeding, and of pollen 



transference by its visitor, with copious explanations there- 

 to. 



6. Specialization miscarried. 



Among our showy flowers are a few possessing the charac- 

 teristics which elsewhere we find associated with insect aid 

 in pollen distribution, and which are never or rarely visited 



