THE FLO WEEING PLAJ<fT — SEEDS 341 



done for the starcli tests, boil the pieces in 

 water for a few minutes, then pour into the 

 test-tube ten or twelve drops of sodium hy- 

 drate and one or two of the copper sulphate, 

 and boil again. Does the color indicate the 

 presence of an albuminous substance ? 

 4. Kepeat the last experiment, using a few drops 

 of Millon's reagent in place of the other two 

 chemicals. If the contents of the test-tube turn 

 pink or red the presence of an albuminous sub- 

 stance is indicated. 



IV. — Microscopic Examination of Starch am,d Aleurone. 

 Mix a pinch of starch and some water together in a 

 watch-glass, then put a drop of the mixture un- 

 der the microscope, and note the shape, size, col- 

 or, and structure of the starch grains. Carefully 

 run a drop of iodine under the cover-glass, and 

 note the effect on the starch. "With a sharp ra- 

 zor cut a very thin section across a softened cotyl- 

 edon of a bean, examine the section under the 

 microscope, and note how the starch is stored 

 away in the cells. Does this give you any clue 

 to the explanation of the results obtained in 5 

 under "Tests for starch" ? Test the section with 

 iodine. Note the very small aleurone grains in 

 the starch-bearing ceUs. What color do they as- 

 sume when stained with iodine ? Note the aleu- 

 rone grains stored in the cells near the surface of 

 the cotyledon. Draw. 



Focus upon the surface of a cell-wall, and no- 

 tice the small circular openings, the ends of 

 canals, which perforate the wall. Focus upon 

 the edge of a wall between two cells, and note 



