1 12 NEOTTEiB. Chap. IV. 



proboscis causes the rostellum to sj)Iit in front and 

 behind, and frees the long, narrow, boat-formed disc, 

 wliich is filled with extremely viscid matter, and is sure 

 to adhere longitudinally to the proboscis. When the 

 bee flies away, so surely will it carry away the pollinia. 

 As the pollinia are attached parallel to the disc, they 

 adhere parallel to the proboscis. When the flower 

 first opens and is best adapted for the removal of the 

 pollinia, the labellum lies so close to the rostellum, 

 that the pollinia attached to the proboscis of an insect 

 cannot possibly be forced into the passage so as to 

 reach the stigma ; they would be either upturned or 

 broken off: but we have seen that after two or three 

 days the column becomes more reflexed and moves 

 from the labellum, — a wider passage being thus left. 

 When I inserted the pollinia attached to a fine bristle 

 into the nectar-recej)tacle of a flower in this condition 

 (n, fig. B), it was pretty to see how surely the sheets 

 of pollen were left adhering to the viscid stigma. It 

 may be observed in the diagram, B, that owing to the 

 projection of the stigma, the orifice into the nectar- 

 receptacle (n) lies close to the lower side of the flower ; 

 insects would therefore insert their proboscides along 

 this lower side, and an open space above is thus left 

 for the attached pollinia to be carried down to the 

 stigma, without being brushed off. The stigma evi- 

 dently projects so that the ends of the pollinia may 

 strike against it. 



Hence, in Spiranthes, a recently expanded flower, 

 which has its pollinia in the best state for removal, 

 cannot be fertilised ; and mature flowers will be ferti- 

 lised by pollen from younger flowers, borne, as we 

 shall presently see, on a separate plant. In con- 

 formity with this fact the stigmatic surfaces of the 

 older flowers are far more viscid than those of the 



