54 NATURE SKETCHES IN TEMPERATE AMERICA 



and specifically adapted to those of the insect life which they 

 shelter. Yet they are produced by a growth of the plant itself 

 when suitably stimulated by the insects' inoculation — or, ac- 

 cording to recent observations, by emanations from the bodies 

 of the larvse which develop from eggs deposited in the 

 plant by the insect. Evolution may have acted through the 

 insects, for "it may very well have been that natural selection 

 would ever tend to preserve those individual insects, the quality 

 of whose emanations tended to produce the form of galls best 

 suited to nourish the insect progeny; and thus the character 

 of these pathological growths may have become ever better 

 adapted to the needs of the insects." 



The Guests of the Wild Bergamot 



In late summer the wild bergamot often grows in clumps 

 covering large patches of ground, in pastures, fields, and road- 

 sides. Where these flowers are thus assembled, bunil)lebees 

 and butterflies are often seen drinking the sweets. It is not 

 until one carefully studies the flowers of this j)lant, together 

 with its insect guests, that some interesting facts are brought 

 to light concerning adaptations. In the first place, the tubes 

 of the flowers are seen to be c|uite long, indicating that they 

 are more nearly adaj)ted for long-tongued insects such as 

 butterflies and moths. 



Accortling to Robertson, the peculiar form of the tube, the 

 two-lipped corolla, and the position of the stamens and style, 

 indicate that the flower is a modification of a flower originally 

 adapted to bumblebees. The level-topped heads, the erect 

 corollas, the exj)osed organs, and rose color make it an attrac- 

 tion for butterflies, — the principal guests. Pammel says that 

 the Iowa flowers, as well as those of Wyoming and Colorado, 

 are frequently visited by bumblebees, though butterflies are 

 not uncommon on the flowers in Iowa. In Michigan, I have 

 found that the bees far outnumber the butterflies as frequent- 

 ers of the flowers. 



These flowers are probably in the process of active changes 

 from bee flowers to butterfly flowers. The change is, perhaps, 

 somewhat hindered, owing to the different insect visitors they 



