4 STUDY OF COMMON PLANTS. 



II. With a sharp knife make a median longitudinal 

 section perpendicular to the flat sides of the grain. Re- 

 peat the process, if necessary, until a good specimen is 

 secured. Observe on the cut surface 



1. The strong external membrane composed of the unitecU 



coats of the fruit and seed. 



2. The endosperm, a tissue containing starch and other 



food materials, very hard in the dry grain, but 

 easily cut in one that has lain some time in water. 



3. The embryo, with its conspicuous organ of absorp- 



tion, scutellum, the latter in close contact with the 

 endosperm. 

 Draw the section. 



III. Remove the entire embryo from a grain that has 

 been soaked. Dissect out the parts enclosed in the 

 scutellum. Compare them with the same parts as seen 

 in section. Note 



1. The radicle pointing toward the small end of the 



grain, its end covered by the root-sheath. 



2. The caulicle, attached to the scutellum, and termi- 



nating above in 



3. The plumule. 



IV. Take a series of transverse sections and locate 

 each one by comparing it with a longitudinal section. 

 Repeat this until you are perfectly familiar with all the 

 parts and their relative position. 



V. Study a grain of corn that has sprouted. What 

 changes has the embryo undergone? 



VI. Collect as many varieties of corn as you can and 

 compare them. 



