22 



ELEMENTS OP BOTANY. 



Test in this manner wheat (in the shape of flour), oats (in oatmeal), 

 barley, rice, buckwheat, flax, rye, sunflower, four-o'clock, morning-glory, 

 beans, peanuts, hazel-nuts, and any other seeds that you can get. 

 Report your results in tabular form as follows : 



Much Starch. Little Starch. No Starch. 



Color, blackish or Color, pale blue or Color, brown, orange, 



dark blue. greenish. or yellowish. 



31. Microscopical Examination of Starch. — Examine starch in water 

 with a rather high power of the microscope (not less than 200 diameters). 



Pulp scraped from a potato, wheat 

 flour, the finely powdered starch sold 

 under the commercial name of "corn- 

 starch " for cooking, oatmeal and buck- 

 wheat finely powdered in a mortar, will 

 furnish five excellent examples of the 

 shape and markings of starch-grains. 

 Sketch all of the kinds examined, tak- 

 ing pains to bring out the markings.' 

 Compare the sketches with Figs. 10 

 and 11. 



With a medicine-dropper or a very 

 small pipette run in a very little iodine 

 solution under one edge of the cover- 

 glass, at the same time withdrawing a 

 little water from the margin opposite 

 by touching to it a bit of blotting-paper. 

 Examine again and note the blue color- 

 ation of the starch-grains and the un- 

 stained or yellow appearance of other 

 substances in the field. Cut very thin 

 slices from beans, peas, or kernels of corn ; mount in water, stain as 

 above directed, and draw as seen under the microscope. Compare with 

 Figs. 10 and 11. ^ Note the fact that the starch is not packed away 



Fig. 10. — Starch-Grains stored in 

 Cell in a Grain of Indian Corn. 



1 The markings will be seen more distinctly if care is taken not to admit too much 

 light to the object. Rotate the diaphragm beneath the stage of the microscope, or 

 otherwise regulate the supply of light, until the opening is found which gives the 

 best effect. 



2 The differentiation between the starch-grains, the other cell-contents, and the 

 cell-walls will appear better in the drawings if the starch-grains are sketched with 

 blue ink or a fine blue pencil. 



