22 NORMAL AND EXPERIMENTAL POLLINATION. 



Perfumes. — Sachet powders and perfumes of various sorts were also 

 tried, but without positive results. Bombus juxtus and B. bifarius hovered 

 above the flowers without landing in many cases, and in others flew about 

 as if not noticing them at all. In one case juxtus alighted at a flower with 

 arbutus sachet and took nectar as if noting no change. In general, if 

 Bombus noticed the odor at all, it seemed repelled rather than attracted by it. 



SUMMARY. 



In general, the bumble-bees had less trouble with horizontal than with 

 inverted racemes, though there were marked individual differences. Some 

 bees passed readily from normal to inverted flowers, adjusting their behavior 

 to each without apparent difficulty. The use of cotton usually prevented 

 landing, and this was frequently the case also when the stamens were 

 removed. In spite of individual departures the other mutilated flowers 

 were usually visited about as much as normal ones. In the competition 

 study, however, those with the hood split or removed received many more 

 visits, while those with the hood and nectaries gone received 3 inspections to 

 one visit, and those with cotton over the stamens obtained but rare inspec- 

 tions. 



No distinction was made between white and purple in the normal flowers, 

 but blue and purple were given a decided preference over the other colors in 

 the case of artificial and painted ones. Since white-crepe corollas with 

 natural centers were visited normally, the choice appears to have been 

 determined largely by the colors regularly present in the species. With 

 the exception of white and blue, none of the artificial flowers yielded visits, 

 though some of these were inspected. Painted flowers, on the other hand, 

 received a third to a half as many visits as normal ones. The addition of 

 honey did not render the flowers more attractive, and no positive results 

 were obtained with perfumes. 



DELPHINIUM SCOPULORUM. 

 NORMAL POLLINATION. 



Habit and structure. — The anthers are very conspicuous in young 

 Delphinium flowers. They become erect when mature, taking a position 

 very near the opening into the nectary and after dehiscence they bend down 

 again. The two petals, which have the tips deflexed, then close together 

 over the shrunken anthers. As the stigmatic surfaces mature, the styles 

 bend up, bringing the stigmas near the opening of the nectary (plate 2). 



Behavior. — Bombus edwardsi and juxtus are the most frequent visitors 

 to Delphinium. When both species are present, edwardsi visits many more 

 flowers than juxtus. The latter uses the two lower sepals for a landing- 

 platform, the forelegs resting on the front spur of the petals or on the sides 

 of the sepals. After landing, it moves the head forward above the stamens, 

 pushes the ligule down the spur, and takes nectar. While it comes for 

 nectar alone, at the same time pollen collects on the legs and thorax. The 

 flow of nectar in these flowers must be rapid, as one individual went twice 

 to 15 flowers on the same plant and to 9 flowers three times in succession 

 while on one trip, and another individual visited 22 flowers twice on the 



