GROWTH OF PLANTS FKOM THE SEED. 21 



you suggest any reason for this difference? How 

 do the other seedlings compare in this respect? 



II. Compare the seedlings of Indian corn and wheat 

 that have attained the height of several inches. 



1. Describe the cotyledon. Has it undergone any 



change during the process of germination ? ^ 



2. Is there a taproot? 



3. Mention all the points in which the two plants are 



alike ; those in which they differ. 



III. Compare the seedlings of the Indian corn and 

 wheat with those of the pea, bean, etc., previously studied. 

 Point out all the essential differences, noting especially 



1. Number of cotyledons. 



2. Venation of foliage leaves. 



3. Position and form of leaves. 



4. Presence or absence of a persistent taproot. 



IV. Examine seedlings of the white pine or other species 

 of pine. In what important feature do they differ from 

 any of the young plants thus far studied? 



V. Summarize your observations and show how the 

 class to which a plant belongs may be determined by 

 inspection of the seedling.^ 



VI. Comparing the seedlings of different dicotyledonous 

 plants (beans, sunflower, etc.), ascertain whether any of 

 them have the two cotyledons unlike in size or shape. Is 

 there anything to indicate that the form of the embryo 

 is determined by that of the seed ? ^ 



1 The protective sheath is regarded as a part of the cotyledon, while 

 the other part, the scutellum, remains in the grain. Cf . Luhbock, Seed- 

 lings, II, p. 587. 



2 Cf . Gray, Structural Botany, Chap. II. 



' Lubbock, Seedlings, I, pp. 30-34, 75-77. 



