480 



STRUCTURE AND LIFE HISTORIES 



ments and drugs. The features of the flower are illus- 

 trated in Fig. 364. 



422. Nightshade Family (Solanaceae). The Night- 

 shade family is of interest chiefly because it contains 



FIG. 364. Salvia sp. (One of the Labiatae). a, flower bud; b-f, 

 various views of the open flower; an., anther; st., stigma; x, projections 

 near the base of the filaments. The lead pencil is made to imitate an 

 insect visiting the flower for pollen. By pressure at the base of the fila- 

 ments, the anthers are brought into contact with the surface of the pencil, 

 which thus becomes covered with pollen. When the next flower is visited 

 the stigma, having then bent down and spread apart, receives the pollen 

 from the other flower. Thus is accomplished cross-pollination. In b, 

 before the visit of the insect, the stigmatic surfaces are still in contact, so 

 that pollination is not possible. 



several genera of very great economic importance, viz.: 

 potato (Solatwm tuberosum), tobacco (Nicotiana Tabacum), 

 tomato (Lycopersicum esculentum), and several medi- 



