INTRODUCTORY LESSONS. 



IX 



begins to grow a " big root." If deeply iilauted, the seeds may grow as 

 represented in Fig. 14. Orange seeds may have puzzled you, but now 



14. Germinatinj seeil of Big-root (MegarrMza) three fourths natural Bizo. 



two or three plumules and as many radicles growing from one 

 seed prove that it has more than one embryo. You readily 

 distinguish the grass-like plumules of the monocotyledonous 

 seeds from the broader leaved plumules of the dicotyledons. The rad- 

 icles, too, send out roots in a differ- 

 ent way. (Figures 15 to 17.) 



11. By this time you cannot fail 

 to see that the embryo i.s a Utile jilant 

 in the seed. The radicle answers to 

 the stem and roots; the cotyledons 

 are leaves, and the plumule is a hud 

 from which is to grow the entire 

 above-ground portion of the jilant. 

 Study the relations between the facts 

 you observe until you can, at least, 

 answer the following — 



15. Germinating corn. ] 6- Wheat. 17. 

 Wild oats; a. colorless sheath inclosing the first 

 plumule leaf b; r, the twistcrl and bent beard 

 which enables it to plant itself. 



Questions. — 1. How many coats have 

 most of the seeds which you have examined? 

 2. What part or parts of the embryo be- 

 come green ? 3. What causes tlie green- 

 ness of plants ? 4. What kind of cotyledons remain underground in germination ? 



5. What can you say of tlie jjlumule of embryos whose cotyledons become leaf-like ? 



6. Do the cotyledons of alljuminous dicotyledons appear above ground? 7. Why 

 should tlie i)lumule of a bean be larger than that of a squash ? 8. What becomes of 

 the albumen in a seed? 9. What nourishes the growing radicle and plumule of an 

 acorn or a pea ? 10. Can you give reasons for calling the cotyledons seed-leaves 



