TRANSFERENCE OF POLLEN 



283 



and tongues, or some particular form and weight of body. In 

 flowers of this character, the insects during their search for nectar, 

 touch the anthers, and the pollen becomes dusted on to their 

 bodies, often at some particular point, which point is brought into 

 contact with the stigma of a flower subsequently visited, and cross- 

 pollination is effected. 



An example of the adaptation of a flower to the visits of 

 large bees may be studied in the common White Dead-Nettie. 

 {Lamium album L.) (Fig. 102). The flower has a conspicuous. 



Fig. 102. — I. Flower of white dead-nettle {Lamiuw 

 album L). 2. Section of the same ; s stigma ; 

 a stamens ; r ring of hairs ; n nectary. 



white, two-lipped corolla. The upper lip {u) is arched and 

 protects the pollen from being washed away by rain ; it also 

 prevents rain from passing down to the nectary which is present 

 at the base of the ovary («). When visiting such a flower, the 

 bee alights on the lower lip (/) of the corolla which acts as a 

 convenient landing-stage, and pushes its head down the tube 

 of the corolla in search of the nectar concealed below. The 

 body of a large bumble bee or a hive bee fits almost exactly 

 into the mouth of the corolla, and the back becomes dusted with 

 pollen from the anthers {a) under the upper lip {u). On enter- 



