THE SPERMAPHYTES. 



237 



amine it by reflected light for marks made by the cor- 

 roding action of the sap from the root hairs. Touch the 

 root hairs of some of the plants with blue litmus paper. 

 The change of color from blue to red shows the presence 

 of an acid. 



15. Show that carbon dioxide is given off by growing 

 plants. 



a. Soak Beans or Peas in water 

 over night, place them in a mod- 

 erately warm place on wet paper 

 during the day, and at night fill a &j 

 500 c.c. flask one third full of them. 

 Stopper the flask and keep it in a A 



warm room over night. In the " 



morning lower a lighted splinter into FlG - 161 - Arrangement 



. , a , m, T . i ,1 of apparatus to show 



the flask. Ihe carbon dioxide that that carbon di0 xide is 

 has been developed by the germi- given off by a s ro g 



J plant. (After Mangin.) 



natmg seeds puts out the flame. 



b. Place a healthy growing plant under a bell jar over 

 night with a beaker of clear lime water. In the morning 



notice that the union of the carbqn 

 dioxide given off by the plant with 

 the lime water has formed a film or 

 cloudiness of carbonate of lime. 



16. Show that carbon dioxide is 

 necessary for growing plants. 



a. Boil some water to expel the 

 carbon dioxide contained in it. After 

 it has cooled, cultivate in it any plant 

 that thrives wholly submerged in 

 water. The experiment is most suc- 

 FIG. if>2. Arrangement cessful when the vessel in which the 



of apparatus to show , J , . .. , 



that carbon dioxide culture is made can be closed by a 



is given off by grow- stopper bearing a bulb tube Contain- 

 ing seedlings. (After 



Sachs.) mg caustic potash or caustic soda 



