18 



NORMAL AND EXPERIMENTAL POLLINATION. 



Side petals removed. — Some bees evidently noticed the changed appear- 

 ance brought about when these were removed, and hovered above the flowers 

 without landing. However, most of them seemed to observe no change, for 

 they landed and sucked nectar as if the flowers were normal, and even came 

 back a second time. The second pair of legs in these cases was crowded 

 closer to the base of the stamens and rested there. Flowers with side 

 petals removed were also placed in the horizontal position with the hood 

 pointing upward. One bifarius treated these flowers as it did Rosa and 

 tumbled about on the stamens, collecting pollen and making no effort to 

 get nectar. Another followed and did the same thing. This was in marked 

 contrast to all other observations on normal Aconitum, in which Bombus 

 had never made any effort to collect pollen. Ordinarily, the pollen was 

 collected accidentally as the body moved back and forth across the stamens 

 in the act of gathering nectar. 



Competitive relations. — The five types of mutilation were represented 

 by 5 flowers each, and these were arranged with 25 normal ones (plates 

 15 and 16). Table 2 gives the results; mere inspections are indicated 

 by an i. 



Table 2. — Visits to normal and mutilated flowers. 



The number of visits to the mutilated flowers was nearly a half greater 

 than those to the normal, due chiefly to the response to the flowers with 

 the hood split. This greatly increased the extent of the color surface and 

 the attraction even to a greater degree, as each flower received 4 times as 

 many visits as a normal one. Since those with the hood off averaged 

 nearly twice as many visits as the latter, the exposure of the nectaries 

 evidently played a part in the attraction. The other mutilations were 

 visited about the same as the normal flowers, except where cotton was 

 present, this change being noted even in rapid flight. Individual differences 

 in behavior were especially noted in the case of the flowers with the hood and 

 nectaries removed. Three bees inspected these flowers to one that landed, 

 and of the latter some flew away at once, while others extended the ligule 

 several times in the endeavor to find the opening to the nectary. 

 ARTIFICIAL AND PAINTED FLOWERS. 



Normal colors. — The flowers of Aconitum columbianum are either 

 blue-purple, or white. The plants studied grew along brook-banks and 

 were lighted by sunflecks, which made the purple flowers more conspicuous 

 than the white ones, though the two were equally numerous. The response 



