THE DEHISCENCE OF ANTHERS BY APICAL PORES. 



233 



position and the pollen collects in the small portion of the 

 anther until by repeated compressions it shall all have been 

 ejected. The stigma projects beyond the anthers and so is 



first touched by the 



visiting 



bird. Presumably other 



B. Ben- 



thamianum 



seem from the floral structure to be 



dependent upon bees for pollination. 



Very interesting observations were made by Burck upon 

 Memecylon edule var. ramiflorum. He describes the prom- 

 inent, active, yellow nectary on the dark violet connective 



spur 



He 



fr 



destructive ant by smaller ones which secure nectar secreted 

 from the outside of the calyx tube, but not from the stam- 



As pollinators he found small, active flies 



mal glands. 



Aristolocl 



These flies do not seem to fear the ants and he suggests 

 that after the flower had developed in adaptation to bee 

 visitors, these found the more recently arriving ants uncon- 

 genial, and upon their desertion of the plant another adap- 

 tation to insects of a very different type became necessary 

 and then the recent staminal nectaries arose. 



As pointed out in the descriptive portion of this paper, 

 the disposition of the petals in the Melastomataceae is 



Brachyot 

 cleistopetala 



do Itatiaia of Brazil, as described by Ule, 



The discussion of structural 



very rarely campanulate. One 

 has been described above. In P 



from 



the flowers never open 



points need not be repeated here. 



He 



first suspected 



Bo 



repeated observations revealed only a small ant covered 

 with pollen. A larger species of ant 

 Other forms found in the mountains 

 pendulous campanulate flowers. 



P. hospita, have 



According 



Darwin Centradenia il 



Rh 



glandulosa, Monochaetum ensiferum, Heterocentron Mexi- 

 canum and snecies of Pleroma are self sterile or but rarely 



