(224 MISSOURI BOTANICAL GARDEN 



is, he thinks, their protection from the insect visitors. 

 According to the observations of O. Schmiedenknecht this 

 species in the garden at Buitenzorg is visited principally 

 by species of Ceratina. C. bacilluris has indurated 

 anthers, so that, according to Burck, the insect can secure 

 pollen only by inserting its proboscis into the terminal 

 pores. Knuth speaks of the anthers being so completely 

 milked out that only a few grains remained. In the 

 Buitenzorg garden, 4 species of Xylocopa and unidentified 

 Syrphidae were observed as visitors. 



C. alata has been described by Burck, Lindnian, Ducke, 

 and Knuth. Lindman saw large and small bees visiting 

 this form in large numbers. He states that in this species, 

 as also in C. aculcata, the large anthers sometimes con- 

 tained no pollen even in the bud. Ducke saw at Para and 

 Macapa, 4 species of Centris, 3 of Xylocopa and 4 of 

 Euglossa. At Buitenzorg, Ceratina was the principal 

 visitor observed. 



Some of the species studied by Knuth at Buitenzorg have 

 already been mentioned. We may summarize his observa- 

 tions on the other species by saying that he usually found 

 only Xylocopa as a visitor. In rare cases he observed 

 PodaliriuH zonatns and Megachile opposita. Centris and 

 Euglossa do not occur there. O. Schmiedenknecht also 

 observed several species of Ceratina on Cassia flowers at 

 Buitenzorg. Knuth thinks that cross fertilization is favored 

 since the projecting stigma will be touched first by a visit- 

 ing insect. In all cases supplementary self-pollination may 

 occur when the flowers are visited by bees, but spontane- 

 ous autogamy he considers possible only in the species with 

 small flowers which close after a time, bringing the stigma 

 into immediate contact with the anthers. In St. Louis, I 

 have taken Bombus and smaller bees collecting pollen from 

 C . sophera. 



According to Miiller, C. multijuja at Blumenau, South 

 Brazil, is visited by Xylocopa artifex and another large, 



