144 COLLEGE BOTANY 



of weak iodine and note the yellowish tint of the crystalloids and com- 

 pare with 2. 



Exercise 5. Repeat No. 4, using bean seeds. 



Exercise 6. Examine a cross-section of a grain of wheat {mount the 

 section in glycerine ) . Note the seed and ovary coats, the starch grain 

 and the aleurone in special cells ("gluten sacs") near the outside. Com- 

 pare with potato and pea. 



Exercise 7. Examine the starch from the semi-transparent part of a 

 grain of corn. Compare with the preceding. 



Exercise 8. Examine the starch from a grain of oats. Compare with 

 the preceding. 



Exercise 9. Examine a fragment of lamina (scale) of an onion. Note 

 the crystals, mostly calcium oxalate and some few calcium carbonate. 



Exercise 10. Examine a cross-section of a leaf of a, rubber plant 

 (Ficus elasticus) . Note the large crystals (Cystoliths) . 



Exercise 11. Examine a thin section of Dahlia root that has been pre- 

 served in glycerine or strong alcohol. Note sphaerocrystals of inulin. 



Exercise 12. Examine thin sections of rhubarb and note the calcium ox- 

 alate crystals. 



Exercise IS- Make a. solution of glucose in a test tube; add Fehling's " 

 solution and heat. Describe the reaction. 



Exercise H- Make a solution of cane sugar in a test tube. Add Fehl- 

 ing's* solution. Compare with Exercise 13. Add a few drops of hydro- 

 chloric acid, boil, neutralize with KOH (to litmus) and repeat the 

 Fehling's test. Compare with Exercise 13. 



Exercise 1.3. Put 10 grams of ground malt into 100 ce. of cold water. 

 Shake, allow to stand for four hours and filter. The liquid is an extract 

 of diastase. 



Make a thin paste of starch and hot water. When cool, put 10 c.c. into 

 each of four tubes. Add 5 c.c. of diastase extract to two tubes and keep 

 at a temperature of about 60 degrees C. for a few hours. Test one of each 

 for starch with iodine and one of each for sugar with Fehling's solution. 



Exercise 16. Soak pieces of beets in warm water. Test the liquid with 

 Fehling's solution. Does it contain sugar? 



Exercise 17. Test several fruits for both starch and sugar. 



Exercise 18. Fats and Oils. Soak bean and castor-oil bean in water. 

 Cut sections and examine for oil; soak in mixture of equal parts of abso- 

 lute alcohol and ether; note the effect. Stain newly cut sections in a 50 

 per cent, alcohol solution of cyanin for 30 minutes and examine. 



Exercise 19. Crush some castor beans, tie in a cloth and soak in xylol 

 or benzine. Squeeze out and remove. Pour the xylol or benzine into a 

 disih and allow to evaporate. The oil remains in the dish. 



Exercise 20. Cut thin sections of a nut and examine under the micro- 

 scope. Note the oil drops in the cells. 



Exercise 21. Tie a small quantity of wheat flour in a bag and knead 

 under a stream of water. The sticky dough that remains is largely pro- 

 tein. The starch was mostly washed out by the stream of water. 



* Fehling's solution (A) — Dissolve 35 prams of copper sulphate in 500 c.c. of water. 

 (B) — Dissolve 60 grams of caustic soda and 1 73 grams of sodium potassium tartrate in 500 

 c.c. of water. 



Use equal parts of A and B, but do not mix until needed. 



