BIOLOGY OF HIGHER SEED PLANTS 

 I 



19 



FIG. 7. Seed and seedlings of morning-glory 



A, section of seed, showing the embryo surrounded by the endosperm ; B, C, D, 



stages in the development and adjustment of the embryo to light and soil; cot, 



cotyledons; pi, plumule 



c. Special motor organs, or pulvini. 



(I) Observe the pulvini of the bean leaves (Figs. 15 and 

 16 of the text). How do they differ from the 

 remainder of the petiole ? Study the form of the 

 pulvinus on leaves in different positions. Do you 



