26 NORMAL AND EXPERIMENTAL POLLINATION. 



arrangement. The two odors were on stalks near enough together for obser- 

 vation, but not so close that the odors were likely to mingle. B. juxtus 

 visited 30 normal flowers and 29 with the carnation odor on one plant and 

 15 normal and 20 with camphor odor on the other. B. proximus went to 



27 normal and 14 with carnation odor, but none with camphor odor. Thanaos 

 martiales visited 1 normal on the carnation stalk, but none with the car- 

 nation odor, and 1 normal and 3 with the camphor odor on the other stalk. 



B. juxtus and proximus both went from normal to flowers with carnation 

 odor and from those to normal flowers. All told, 83 visits were made to 

 normal and 68 to perfumed flowers, the number to carnation being twice 

 that to camphor. 



SUMMARY. 



The experiments with flowers in changed positions indicate that the 

 bumble-bee not only perceives such changes readily, but also distinguishes 

 between the two positions with respect to the ease of landing. In general, 

 mutilated flowers were visited as readily as normal ones, even the removal 

 of the landing-platform causing but temporary difficulty. Individuality of 

 behavior was more or less marked as usual, the removal of the petals having 

 no effect on one day and leading to such flowers being completely ignored on 

 another. As a rule, the bees were quick to learn the significance of the 

 different changes, solving the problem of landing after a few attempts. 

 The response to paper flowers with natural centers was in sharp contrast to 

 that to painted flowers; the former received but one visit to 125 for normal 

 flowers, while the latter yielded one to each 7 for the normal. This suggests 

 that the eyes of the bumble-bee are even more accurate than our own in 

 perceiving small differences of color and form. The figures in the case of 

 visits to perfumed flowers are not decisive, though they indicate that the 

 bees found the added odor somewhat disturbing. 



The experimental results with Aconitum and Delphinium are essentially 

 in harmony, as might be expected from the ecological similarity of the 

 flowers. Changes in position and form produced much the same response, 

 as did paper flowers and added perfume. In the case of painted flowers of 

 Aconitum, however, there were more than half as many visits as to the normal 

 ones, the ratio being 1:1.7 in contrast to 1 :7 for Delphinium. 



RUBUS DELICIOSUS. 

 NORMAL POLLINATION. 



Habit and structure. — The bushes of this species are tall and spreading, 

 the branches profusely laden with flowers which are the showiest in bloom 

 during its period. With respect to attraction the flower consists essentially 

 of a mass of yellow stamens surrounded by very large white petals, and 

 possesses a pleasant odor. The corolla is widely expanded and the stamens 

 fully exposed. The nectar is formed at the base of the stamens, where it 

 appears as a circle of tiny drops. 



Behavior. — Bombus juxtus collects pollen chiefly with the hind legs 

 as it tramples about, packing it in large masses on them, the hairs of the 

 body becoming well dusted in the process. As it moves about, pollen is 



