12 BOTANY FOR BEGINNERS CHAP. 



which correspond to the testa and tegmen of the bean. The other 

 layers belong to the fruit, for the grain of wheat is in reality a fruit 

 (p. 19). 



(ii) The micropyle is hidden by the coverings of the fruit and cannot 

 be seen, but at one -end of the grain a firmer portion will be found, 

 which is the embryo, and above the embryo a softer portion, the 

 endosperm, can be distinguished. This is reserve food material for the 

 use of the young plant. 



(iii) On the cut surface of the embryo, in contact with the endosperm, 

 a single cotyledon will be found ; and on the outside of this an upper 

 portion, the plumule, and a lower portion, the radicle, can be made 

 out. 



The following table will show the relation of the different 

 parts found in the grain of Indian Corn. 



Indian Corn. 



I I. 



Kernel. Covering. 



L_ _ I 



I I I " I 



Embryo. Endosperm. Spermoderm. Fruit. 



I I I 



Radicle. Cotyledon. Plumule. 



Dicotyledons and Monocotyledons. In both the Bean 

 and Indian Corn seeds, the embryo consists of radicle, plumule 

 and cotyledons, but the number of cotyledons differs. 



The Indian Corn has only one cotyledon, but the Bean 

 possesses two. Those plants which possess two cotyledons are 

 referred to as Dicotyledons, and those with only one as 

 Monocotyledons. The Bean belongs to the former, and the 

 Indian corn to the latter. 



Germination of Seeds. The early stages of the develop- 

 ment of the embryo are spoken of as germination. If the seed 

 is examined during germination, we can clearly see how the 

 various parts which are found in the embryo act during that 

 process. 



EXPT. 4. Obtain a few Mustard seeds, and place them on a piece 

 of flannel stretched on a saucer. Keep the flannel damp and warm. 

 Examine the seeds from day to day, and notice : 



(i) That they begin to sprout. This is the result of the moisture and 

 heat. At one place a small swelling appears, which is due to the radicle 

 pushing its way through the micropyle. 



