RESUME. 89 



lated flowers of Monarda and to flowers of other species was practically the 

 same, though this is doubtless only a coincidence. The normal flowers 

 were about thrice as attractive as these two groups, due in part to habit 

 and in part to the mutilated ones being often less conspicuous and demanding 

 unusual methods of approach. 



The number of visits to the various mutilations were determined by 

 four factors, namely, conspicuousness, ease of landing, accessibility, and 

 exposure of nectar. Flowers with the upper lip removed were visited, 

 most, since they were least changed in essential respects, the lower lip 

 constituting the landing-platform and the attractive banner. The removal 

 of the stamens in addition diminished the visits more than half, by affecting 

 landing and eliminating the attraction of pollen, in the case of Clisodon 

 especially. Visits to flowers without the lower lip were about a fourth as 

 numerous as to those with the upper lip removed, due to their being less 

 conspicuous and deprived of the landing-platform. Blossoms with the corolla 

 shortened to half its normal length received an equal number of visits, a 

 puzzling fact when taken in conjunction with the response to flowers with 

 both lips cut off. The difference here is evidently to be explained by the 

 greater readiness with which the odor of the nectar escapes, as well as by the 

 greater ease of access for certain bees. The respective values of the upper 

 lip, stamens, lower lip, and both lips in attraction and guidance are probably 

 well indicated by the number of visits, viz, 220, 101, 58, and 11. 



While Monarda exhibits a wide range of visitors, only 8 of these are 

 frequent and 5 important, namely, Clisodon, Bombus appositus, B. juxtus, 

 Erynnis, and Argynnis. Clisodon paid nearly as many visits to the normal 

 flowers as the total for the other four species, but it made only 1 visit in 10 

 to the mutilated flowers in contrast to about 1 to 2 for Erynnis and 1 to 3 

 for B. juxtus. Its large number of visits is to be explained chiefly by the 

 fact that many of them were made for pollen alone and did not involve 

 landing. It is interesting to note that the longer-tongued B. appositus 

 visited nearly twice as many normal flowers as juxtus, while it went to only 

 1 mutilated flower in 9 to 1 in 3 for juxtus. Among the butterflies, Erynnis 

 visited more than a half again as many normal flowers as Argynnis, but four 

 times as many mutilated ones. In spite of its apparently less accurate 

 movements, Erynnis was considerably more successful than B. juxtus and 

 several times more so than Argynnis in solving the difficulties presented by 

 the mutilated flowers. 



RESUME. 



Variation in number of visits. — The special studies of the abundance 

 of visitors and the frequence of visits made with Rubus deliciosus, Geranium 

 caespitosum, Chamaenerium angustifolium, and Pentstemon glaber show that 

 time, place, and conditions produce great fluctuations in the species and 

 numbers of visitors and visits. Considerable differences in these respects 

 between early, mid, and late season would be expected, but almost as great 

 differences may be found between successive days or hours, as, for example, 

 in the case of Chamaenerium, where the number of visitors and visits for 

 two successive hours were 21:728 and 4:204, or of Rubus deliciosus, for 

 which the figures for Apis were 22:127 and 5:5. The effect of even a 



