THE RELATION OF THE PLANT TO WATER 169 



Exervise 13. Fill a tliin test tube with dry peas. Tie a cloth over the 

 mouth of the tube and place in water for 24 hours. Note the result. 



Exercise I'l. Put 100 to 200 grams or more of well powdered starch 

 that has been dried at 105 degrees C. in each of two glasses and 100 to 

 200 c.c. of water in a third glass. Put tested, uniform thermometers in the 

 glasses and set in a water bath at room temperature until the thermom- 

 eters register the same. Pour the water into one of the glasses \vith 

 starch and mix thoroughly. Note the rise in temperature as compared 

 with the others. 



Exercise 15. Fill a test tube about two-thirds full of thick, colored 

 molasses, using care not to smear the sides. Very carefully and gently 

 add an equal amount of water. Note gradual mixing due to diffusion 

 from day to day. 



Exercise 16. Place a large crystal of potassium ferrocyanide or 

 chromic acid in a glass of water. Note the gradual diffusion. 



Exercise 11. Place a drop of copper sulphate in a 5 per cent, solution 

 of potassium ferrocyanide and note the formation of the semi-permeable 

 precipitation membrane. 



Exercise Ifi. Make 250 c.c. of .5 gram molecular (M) solutions of potas- 

 sium nitrate and sodium chloride. Using these as stock solutions, make .10, 

 .20, .30, and .40 molecular (M) solutions of each in quantities of about 

 25 c.c. Select lettuce, radish or mustard seedlings of about the same size 

 and suspend one in each solution. Note the time of wilting of each. 

 Examine the root-hairs under the microscope for plasmolysis. 



Exercise 19. Use the same solutions as in 18. Split the flower stalks 

 of the dandelion into four parts and dip into water. When the spirals 

 are well formed, cut into distinct rings and place one ring in each solu- 

 tion and note the result. Further curling indicates absorption of water, 

 while extension indicates loss of water, i.e., plasmolysis. 



Exercise 20. Fasten; a piece of soaked pig's bladder over the bulb of a 

 thistle tube. Fill the bulb with molasses and suspend in distilled water so 

 that the two liquids are on the same level. Observe from time to time 

 and note the result. 



Exercise 21. Cut two 1 cm. cubes of red beet. Put one in water at a, 

 temperature of 70 degrees C. for 10 minutes. Then put both in lukewarm 

 water and note effect on the color. Explain. 



Exercise 22. Repeat the last exercise, but freeze one cube instead 

 of heating. 



Exercise 23. Turgor. Hollow out three beets or carrots or turnips or 

 potatoes. Fill one with sugar and one with salt. Put all three in' a 

 closed chamber and keep for 24 hours. What is the effect? 



Exercise 2Jf. Wilting. Prepare a, 1, 5, 10 per cent, solution of sodium 

 chloride. Fill three jars and also one other jar with distilled water. 

 Place seedlings in each and note time required for wilting. 



Exercise 25. Cut a fresh section of a beet and keep in alcohol for two 

 minutes. Mount in water and note the effect on the color.. 



Exeroise 26. Cut thin slices of a fresh fleshy root, such as turnip or 

 carrot. Keep in salt solution for one hour and note the effect. Transfer 

 to distilled water for one hour and note the effect. Explain. 



Exercise 21. Cut a section of a fresh garden beet and examine under 

 the microscope. Note the contents of the cells. 



Add a few drops of salt solution and note the effect. 



Wash and remount in distilled water and note the effect. 



