34 



NORMAL AND EXPERIMENTAL POLLINATION. 



the front legs and stores it on the hind ones. Prosopis elliptica works 

 very rapidly with its mouth-parts and with the front pair of legs. It 

 opens the anther with the front legs, scrapes out pollen, and also picks 

 it up from the corolla. Anthophora simillima poises 7 to 15 cm. above the 

 flower, meanwhile buzzing loudly, and then makes a dive for it. While 

 diving, head and abdomen tip are together, and as it lands it grasps the 

 stamens with its front legs and slides down the bunch of filaments. When 

 the anthers are reached, a struggling movement takes place, during which 

 pollen is put on the third pair of legs, when it buzzes into the air again and 

 dives for another flower. It often darts repeatedly into the same flower, 

 apparently getting some nectar during this process. Monumetha albifrons 

 tramples around on the stamens with its head buried in the mass. It moves 

 very rapidly, working all three pairs of legs and storing the accumulated 

 pollen on its ventral scopa. The latter also rubs rapidly against the anthers 

 and collects pollen. Osmia bruneri tramples over the stamens in the same 

 manner as Bombus. Megachile wootoni moves around very rapidly while 

 on the stamens, the first two pairs of legs scraping out the pollen and passing 

 it to the third pair, which place it on the scopa. This is raised in the air 

 and usually does not come in contact with the anthers. 



Table 14 shows the visitors observed during 30 minutes on 42 flowers of 

 Rosa, 14 of which were just opening and the anthers beginning to dehisce. 

 The lists were made on successive days, and exhibit the difference often to be 

 expected. 



Table 14. — Visitors to normal flowers. 



The pollination of the rose appears to have received no attention in this 

 country, but several species have been studied in Europe (Knuth, 1906:348). 

 These are chiefly visited by beetles, though several genera of bees have 

 been taken on R. canina, and two species of Bombus on rubiginosa. 



EXPERIMENTS. 



MUTILATION. 

 Corolla shortened. — The petals of Rosa were cut to half their length, 

 giving the corolla a rotate form. This made them paler in color, as the 

 petals are almost white toward the base. Since the flower is smaller, the 

 stamens also become more conspicuous. At such flowers, Bombus juxtus 

 landed, collected some pollen and then passed on to the next, never securing 

 all of the available pollen at any flower. Monumetha albifrons remained 

 at each flower a long time and collected much pollen. In order to determine 



