ANATOMY AND MORPHOLOGY OF THE FLOWER 237 



phology of these parts, including ovule and pollen-grain, from 

 the start; pupils understand it as readily as they do the 

 formal and partly incorrect morphology current in many of 

 our text-books, and they have nothing to unlearn later. 



It is usually assumed that a perianth tube, such as the 

 Hyacinth has, is composed of united petals and sepals; this 

 is not strictly true, for the tube is probably not made by the 

 union of the bases of petals and sepals, but by a ring of tissue 

 under the bases of the petals and sepals, which is one con- 

 tinuous structure, a sort of ring leaf, and not six united parts 

 (see page 148). The point is very important for an under- 

 standing of the composition of complex flowers. 



The function of pollen and ovule can best be given them 

 through an account, fully illustrated by diagrams, of the process 

 of fertilization. That of calyx can be illustrated by reference 

 to buds where it is a protection to the young parts. As to the 

 showy corolla, its use can be brought out by such a line of 

 reasoning as this : Experiments and observation have shown 

 that better seed is produced when pollen and ovule come 

 from different plants; this requires the locomotion of pollen 

 from one plant to another ; this is often brought about by wind, 

 but that is a very wasteful method ; a much more economical 

 mode of locomotion of the pollen would consist in using some 

 agency which could be made to move from one flower to an- 

 other ; small animals, particularly insects, form such an agency, 

 but some inducement must be provided to make them visit the 

 flowers ; this is generally done by nectar, on which they feed ; 

 but the place where the nectar is must be shown them so they 

 may find it ; this is done either by strong odors, or else by 

 color ; the special structure developed to hold the color is the 

 corolla. Later the argument may be continued thus : not only 

 must the insect be brought to the vicinity of the nectar, and 



