‘18 FOUNDATIONS OF BOTANY 
nary commercial starch as used in the laundry, and as 
sold for food in packages of cornstarch. When pure it 
is characterized not only by its lustre, but also by its 
peculiar velvety feeling when rubbed between the fingers. 
' 22, The Starch Test. — It is not always easy to recog- 
nize at sight the presence of starch as it occurs in seeds, 
but it may be detected by a very simple chemical test, 
namely, the addition of a solution of iodine.! 
‘EXPERIMENT VIII? 
Examination of Familiar Seeds with Iodine. — Cut in two with a 
sharp knife the seeds to be experimented on, then pour on each, drop 
by drop, some of the iodine solution. Only a little is necessary; 
sometimes the first drop is enough. 
If starch is present, a blue color (sometimes almost black) will 
appear. If no color is obtained in this way, boil the pulverized 
seeds for a moment in a few drops of water, and try again. 
Test in this manner corn, wheat (in the shape of flour), oats (in 
oatmeal), barley, rice, buckwheat, flax, rye, sunflower, four-o’clock, 
morning-glory, mustard seed, beans, peanuts, Brazil-nuts, hazelnuts, 
and any other seeds that you can get. Report your results in tabu- 
lar form as follows: | 
Mucu STARCH LITTLE STARCH No STARCH 
Color: blackish or Color: pale blue or Color: brown, orange, 
dark blue. greenish. or yellowish. 
23. Microscopical Examination of Starch.2—- Examine starch in 
water with a rather high power of the microscope (not less than 200 
diameters). 
* 1The tincture of iodine sold at the drug-stores will do, but the solution 
prepared as directed in the Handbook answers better. This may be made up 
in quantity, and issued to the pupils in drachm vials, to be taken home and 
used there, if the experimenting must be done outside of the laboratory or the 
schoolroom. 2 May be a home experiment. 
' 8 At this point the teacher should give a brief illustrated talk on the con- 
struction and theory of the compound microscope. 
