230 A BOOK OF INSECTS 



by Mr. W. H. Lang in the following passage : " If, as is 

 usually the case, the fly approaches the flower on the 

 wing immediately in front, the first part of the flower to 

 come in contact with the lower surface of its body will 

 be the stigma. Alighting on the flower, the insect may 

 be seen, in trying to gain a foothold, to grasp the bases of 

 the stamens and to draw them together with its legs, 

 thus rubbing the anthers against the under surface of its 

 body. This region will, after visiting a flower, be dusted 

 with pollen, and on the insect going to another flower the 

 stigma will receive some of this. If the position of the 

 various parts in the opening flower is taken into account, 

 it will be readily understood that the pollen would not be 

 likely without insect agency to get from the anthers, 

 borne to either side on long stalks, to the stigma, project- 

 ing in the middle line in front. The whole apparatus is, 

 however, suited for cross-pollination by the help of small 

 flies, and the way in which it works can be verified by 

 careful observation of a group of the plants on a sunny 

 day. The reduction in number of the stamens to two is 

 an indication of the precision of the method of pollina- 

 tion." Lastly, in the figwort (Scrophularia) we have a 

 flower which caters especially for wasps, and is almost 

 exclusively cross-pollinated by these insects. The corolla 

 tube is short and swollen. The stamens are four, but the 

 fifth is represented by a petaloid scale which occasionally 

 resumes the functions of an anther. Two large drops 

 of nectar are secreted and lie at the base of the corolla, 

 while the flower exhales a faint, carrion-like odour. The 

 stigma matures first. Later, the stamens become erect 

 and shed their pollen. To get at the nectar, the wasp 

 crawls over the lip of the corolla, and, in the case of the 

 older flower, gets dusted with pollen on the under part 

 of its body. If it subsequently visits a flower in the 



