19 



A new outgrowth, caused by insects, and but sliirhtly 

 moditied in tissue, appears therefore to favor a change of 

 color in stems and leaves, and the same tendency is seen in 

 the petals of flowers. The two upper lobes of Rhododen- 

 dron (Azalea) under a lens will be found to be obscurely 

 wrinkled with slight elevations and de[)ressions. The dots 

 or hyphen-like marks occur on the elevations. A slight 

 change of tissue, and their prominence cause a concentration 

 of coloring matter in the dots, which are always of a deeper 

 shade than the basal color. The beard on the petals of 

 certain species of Iris is doubtless caused in a similar 

 manner by the fretting effects of insects such as bees with 

 sharp clinging claws on a very sensitive surface. It is not 

 improbable that the yellow color of the beard on an other- 

 wise blue flower, is due to the fact that the beard is a com- 

 paratively recent outgrowth of tissue of a different character 

 as regards the cells, and probably of somewhat different 

 functions Calopogon jjuIcheUus has a crest-like outgrowth 

 on the lip, and the teeth-like processes have different colors, 

 white, lemon-yellow, orange and purj)le, according to their 

 varying lengths and forms. 



The central, yellow eye in Pansies has papilhe several 

 times as long as in other parts of the flower. 



A white variety of Weigelia rosea with age changes to 

 pink or rose color, also the two yellow, narrow streaks in 

 the throat, but the area within and about these streaks, 

 being the })art stimulated the most by the bees, becomes a 

 deeper shade than the rest. Catalpa spectosa has two yellow 

 lines and numerous purple dots as honey guides. With age 

 the white ground upon which these markings occur changes 

 to purple, but no other part of the white corolla changes. 

 The influence of the bees is thus plainly indicated in deep- 

 ening color, or producing color where there was none pre- 

 viously. In the morning glory, a rain drop or an insect 

 resting upon a petal, while the sun is shining, is apt to 

 change the color beneath it. 



