64 



Fig. 6. — Front view of column in which necrosis of the ros- 

 iiellum has taken place, thus effecting the same object as in fig. 5. 

 Lettering as before. 



Plate IX. b. 



Column of Thelymitra venosa, Br. (magnified 4 times), show- 

 ing various stages in the process of pollination. 



Figs. 1 and la. — Front and side views of column in early bud 

 before expansion has taken place. The bifid anther-point is higher 

 than the lateral appendages, and the pollen-cases have already 

 begun to dehisce, thus exposing the granular pollen. The turg- 

 escence of the pollen-cases can be particularly well seen in the side 

 view (fig. lay — ap, bifid anther-point; p c, pollen-cases (dehiscing); 

 p, pollen ; s, stigma. 



Figs. 2 and 2a. — Front and side views of the column at a later 

 stage, when the anther has descended to an angle of 45° with the 

 column, and its point has assumed a lower level than the lateral 

 appendages. Pollen is beginning to fall freely upon the stigma. 

 Lettering as in figs 1 and la. 



Figs. 3 and 3a. — A rather more advanced stage than shown in 

 the last figures. Lettering as in figs. 1 and la. 



Figs. 4 and 4a. — Front and side views of the column after 

 expansion. The pollen-cases are retracted and practically empty ; 

 the anther is almost horizontal, and the stigma is swollen and 

 tumid. 



