THE SPERMAPHYTES. 241 



omitting in succession one ingredient of the solution. 

 Place in the sunlight arid under favorable conditions of 

 warmth, and renew the solutions about once a week. 

 From a comparison of the results, what elements do you 

 think are necessary for the healthy growth of green 

 plants. Renew the solutions again, adding the missing 

 ingredients. What is the effect on the plants? Com- 

 pare the root hairs in each case with those formed on 

 plants growing in the soil in the pots. State what you 

 notice. Do the plants grown in watery cultures need as 

 abundant root hairs as those grown in soil ? 



20. Germinate some Beans or Peas until the radicles 

 are half an inch long. Grind them to a pulp with water. 

 Test a portion for sugar as follows : Add a little caustic 

 soda solution and then a little copper sulphate solution. 

 This treatment will give a reddish brown color, if sugar is 

 present. Do the germinating seeds contain sugar? Test 

 another portion of the solution for starch with iodine solu- 

 tion. Do the germinating seeds contain starch? Test 

 another portion of the solution for proteids by adding 

 a few drops of a solution made by dissolving a small drop 

 of mercury in nitric acid. Acid enough must be used 

 to dissolve the mercury entirely. This is known as 

 Millon's reagent ; it gives a red color with proteina- 

 ceous substances. Do the germinating seeds contain 

 proteinaceous substances ? 



21. How do the food materials get into the plants ? 

 Cover the mouths of four thistle tubes with bladder. Fill 

 one of the tubes held mouth down with water containing 

 all the sugar it will dissolve to a point about one centi- 

 meter above the bulb. Stand it mouth down in a beaker 

 of water so that the water in the beaker and the sugar 

 solution in the tube are at the same level. Fill another 

 tube similarly with water, to which a quantity of starch 

 has been added, and arrange it in a beaker of water in the 



CLARK'S BOX. 16 



