26 



GENERAL BIOLOGY 



the n cSr f oia e tubJ mens 



j. The relative fitness of the different visitors to one 

 kind of flower. 



It will have been observed in the course of the field studies 



hitherto outlined, that not all the visitors to one kind of 



flower are equally proficient in obtaining its stores or in 

 transferring its pollen: also, that 

 the manner of visitation is very 

 different in different insects. The 

 butterfly perching atop of a phlox 

 corolla and probing the deep tube 

 only with its long proboscis (fig. 21) 

 could not exchange places with the 

 bee that plunges bodily into the 

 chelone flower (fig. 22): it would 

 meet with Acuities Kke those of 

 the stork of the fable > attempting 

 to dine with the wolf. A more 



careful study of this matter will 



show that the pollination of a 



flower may be well effected by in- 



sects that operate in very different 



ways. 



The following study of all the 



visitors to one kind of flower is in- 



tended to reveal the actual rela- 



tions existing between a flower and 



its visitors, and the relative fitness 



of these visitors. Clearly this fit- 



ness consists in two things: i) 



ability to get the food store the flower offers, and 2) ability 



to transfer pollen from anther to stigma. 



Study j. All the visitors to some common flower. 

 Apparatus needed: insect net, cyanide bottle, lens and 

 note book: use chiefly the two last mentioned. 



FIG. 22. The flower of turtle 

 heads (Chelone glabra), and 

 its visitor (worker Bombus). 





