Studies of Selected Spermatophytes. 249 



would you apply to its leaves ? Make a longitudinal section 

 through the center of an inflorescence which has been only 

 a short time in bloom, and notice the unopened buds at 

 the center and the fully expanded flowers at the margin. 

 The disk from which the flowers grow is the receptacle of 

 the inflorescence (not a flower receptacle). Examine 

 under a lens the apex of an unopened flower and note the 

 number of notches in the corolla indicating the number 

 of petals. What changes does the corolla undergo as it 

 expands into the open flower? Remove an entire un- 

 opened flower from the receptacle of the inflorescence, 

 taking care not to break off the ovary, lay it on the stage 

 of the microscope, and carefully dissect it with needles 

 while looking at it through the lens. How many stamens 

 do you find ? Where are the filaments attached ? How 

 many style branches are there? What relation do they 

 bear to the anthers ? Do the anthers dehisce toward the 

 inside or outside ? Notice the relative heights of stamens 

 and styles in successively older flowers. Note the behavior 

 of the style branches up to the time of the withering of 

 the flower. How is the pollen pushed out from the tube 

 formed by the united anthers ? The stigmatic surfaces 

 being along the inner or opposing faces of the style 

 branches, is it possible for self pollination to take place 

 at any time ? The nectary occurs near the base of the 

 style, and the nectar is expelled into the tubular part of 

 the corolla. See whether the corolla tube ever becomes 

 filled with the nectar. Can insects probe between the fila- 

 ments to reach the nectar ? Observe the behavior of bees 

 on these flowers. To what parts of their bodies does the 

 pollen adhere ? Now state in precise terms all of those 

 facts which have a bearing on the cross or self pollination 

 of this plant. When an inflorescence has once expanded, 



