THE FLOWER. 77 



III. Note all protective and attractive arrangements. 



IV. Compare flowers of a number of different plants 

 with regard to the position of the essential organs. Notice 



1. The length and insertion of the stamens. 



2. Length of style. 



3. Form and structure of the stigma. 



4. Any other particulars in which the long- and short- 



styled forms differ. 



V. Make longitudinal sections of the two forms and 

 sketch in outline. Read Darwin, Different Forms of 

 Flowers on Plants of the Same Species, Chap. I. 



NOTE. It will, of course, be understood that an acquaintance with 

 many more species will be necessary in order to obtain a general concep- 

 tion of the morphology of the flower, and an adequate knowledge of its 

 physiological adaptations. Accordingly, similar studies of other flowers 

 may be made before proceeding farther, or this may be postponed until 

 the families of flowering plants are taken up. In any case the student 

 should now read carefully Gray, Lessons, pp. 79-109, or the equivalent 

 part of the Structural Botany, by the same author. He should also make 

 a constant practice of referring to Miiller, Fertilization of Flowers. 



POLLEN, OVULES, EMBRYO. 



I. Examine with the compound microscope the pollen 

 of a number of different plants, such as pine, lily, pump- 

 kin, mallow, and others. Compare the grains as to size, 

 shape, and surface. Notice whether those disseminated by 

 the wind are characterized by different features from those 

 that are carried by insects or birds. Draw and describe. 



II. Sow various kinds of pollen in watch glasses con- 

 taining sugar solution (3 to 20 per cent). At intervals of 

 a day or less transfer a few grains to the glass slide with 

 a camel's-hair brush and examine microscopically. Some 



