THE DEHISCENCE OP ANTHERS BY APICAL PORES. 223 



species of Augochlora. Trigona ruficrus often bites the 



anther quite in pieces. 



Burck considers that the floral mechanism of Cassia 

 favors autogamy, basing his conclusions on the fact that in 

 several species studied by himself the tip of the pistil 

 returns to the median plane of the flower by a new curva- 

 ture of the style so that it will not come in contact with 

 the region of the insect's body previously supplied with 

 pollen from the pores of the larger stamens, and that in 

 others the stigma comes almost in contact with the tips of 



the stamens. 



Burck' s paper contains some interesting observations, 

 but it seems that his conclusions can hardly be accepted 

 without further investigation. For a more detailed com- 

 parison of his statements and conclusions, reference must 

 be made to his own paper. ^ 



According to him, C. glauca differs from the other 

 species in having coriaceous instead of indurated anther 

 walls. The large bees — Xylocopa and Bombus — which 

 visited this, and other species observed by him, alight in 



flower 



> j 



of the five short stamens or they may destroy in part or 

 entirely both the anther walls and the pollen. Only the 

 two large stamens remain intact and undespoiled of their 

 pollen. Knuth's observations on C. Horsfeldii, considered 

 by some a synonym of C. glauca, confirm Burck's obser- 

 vations on this point. The bee flies directly towards the 



stamens 



when 



these are touched, it is with the ventral surface of the body. 

 He never saw the stigma in contact with the body of the 



"V 



mi 





at the moment when the insect leaves the flower. But 

 even then, the chances are that the dorsal surface of the 

 insect's body, rather than the ventral surface to which the 

 pollen adheres, will touch the stigma. 



The significance of the elongation of these lower anthers 



