Vlll INTKODUCTOEY LESSONS. 



be much easier to make, out the exact shapes and positions of the em- 

 bryos in most albuminous seeds after they have begun to grow. 



6. Monocotyledonous Embryos. Corn, wheat, oats, and possibly a 

 few other seeds in your collection, are different in plan from any yet 

 described. In corn the soft portion called the chit is the embryo. Wheat 

 and oats have smaller but similar embryos. You cannot easily distin- 

 guish the parts of these embryos, but you can, at least, determine that 

 they have not two cotyledons. Really they have one cotyledon, and are 

 therefore said to be Monocotyledonous. When j r ou study the growing 

 seeds you will see how widely they differ from seeds which have 



7. Dicotyledonous Embryos. These are embryos, which, like the bean, 

 have two cotyledons. A few plants belonging to the Pine Family have 



8. Polycotyledonous Embryos. Fig. 12 shows the embryo of the 

 common Willow or Digger Pine, which has more than two cotyledons in 

 a whorl at the top of the radicle. 



9. The Germination of Seeds. Plant the remainder of your seeds 

 those of a kind together in boxes or pots of sand, or any kind of loose 

 soil you can get. Keep this little experimental garden in a warm place, 

 where it can get a bit of sunshine, and water it daily. At intervals of 

 three or four days dig up one of each kind of seed, and, after careful 

 examination, make drawings to illustrate the successive stages of growth. 

 It is of the greatest importance that you repeatedly attempt to draw 

 what you see; it is of the least importance that your drawings are pretty. 



10. You will learn, among many interesting facts, that most seeds 

 are pushed up to the surface of the ground by the growth of the radicle. 

 There the seed-coats drop off (except that in seeds without albumen the 

 cotyledons are apt to slip out of their coats on the way up); the cotyledons 

 Spread apart, become longer and broader, and turn green; lastly, the 

 plumule becomes a leafy stem. Meanwhile, roots grow from the lower 

 end of the radicle. Some cotyledons, like those of the pea, do not ap- 

 pear above ground, but send the plumule up. The seeds of Big-root 

 a pest which grows in nearly every field behave in a remarkable manner. 

 If the seeds are lightly covered, the united stems (petioles) of the cotyledons, 

 by their growth, push the radicle and plumule directly downward four 

 or five inches into the soil, then the plumule comes up, and the radicle 



