142 



COACTIOX: THE INTERRELATIONS OF ORGANISMS 



wise by subjecting them to competition, and was further seen in earlier 

 flowering. 



The gains to the pollinator have to do entirely with the question 

 of food supply, apart from shelter and protection in the case of 

 lodgers. The food may be nectar for the immediate use of the adult 

 or for storage, or pollen for producing bee bread to feed the larvae 





Fig. 33. — Insect pollination: The sphinx moth (Protojxircc quinquemaculatus 

 Haw.) visiting evening primrose. (Photo by Edith Clements.) 



of bees. Both may be gathered from the same species or each one 

 from a different species, but the general effect in pollination is the 

 same. In one-flowered plants, crossing alone can occur, and this is 

 probably the rule with few-flowered ones. However, when the num- 

 ber of flowers rises to hundreds and thousands, the manner of working 

 by bees, butterflies, and hummingbirds in particular renders it prob- 

 able that the great majority will be fertilized by the pollen of the 

 plant that bears them. Furthermore, it is possible for certain sturdy 



