

THE DEHISCENCE OF ANTHERS BY APICAL PORES. 231 



bee's abdomen while a very slight backward pull at once 



raises the anther." 



Forbes and Burck were able to detect differences in the 

 pollen of the two types of stamens. " The pollen from 



stamens 



was very much smaller and of a more 



oval shape ; and while both forms were found on the pistil, 



from the long stamens seemed 



stamened 



Bo 



tubes opened." In a later paper Forbes records 

 senex as a visitor. In his paper on division of labor in the 

 stamens of pollen flowers, Miiller records further observa- 

 tions by his brother in which incipient stages of the color 

 dimorphism were observed in a melastomataceous genus, 

 probably Pleroma. The significance of color dimorphism 

 has already been alluded to under the Solanum-Cassia 



type. 



some 



Purp 



found 



more 



species of Tibouchina for comparison 

 The visitors of these flowers with splen- 

 relatively few while they were much 

 nconspicuous flowers of Croton, Sper- 

 macoce, Sida, etc., growing near by. Butterflies, flies 

 and birds do not visit these forms which secrete no free 

 nectar but offer only pollen diflicult of collection which 

 various pollen-collecting Hymenoptera are able to gather. 

 The pollen is not so dry as in Purpurella 

 sticky. A few times he saw humble-bees 

 flowers, and once he was able to examine in detail the 





visiting 



the 



ie on a shrub of T. Moricandi 

 Kopf noch dem Mittelpunkt de 



und bald einen 



Strauch abgeernt hatte. 



Warsch 



auf und kann dann leicht Fremdbefruchtung 



Haaren 



erzeugen. 



Haufiger sind kleine und winzige Biener 

 gef altete Antherenhaut durchnagen und 

 sammeln, wie ich mich ofter 



iiberzeugt 



und 



sogar 



die 



• 





