LABORATORY AND FIELD WORK 423 



fibers are used in making the different kinds of cord, binding 

 twine, rope, sacking, etc. that you may find in various shops 

 and stores? 



5. What plants growing in your locality are used in any of the 

 following ways : as medicines, for stimulants, for beverages, as 

 sources of oils, waxes, resins, perfumes, or dyestuffs ? 



6. If possible, a visit should be made to a museum in which 

 economic plants and their products are exhibited. Notes may be 

 taken of the different plants observed, of the regions in which 

 they grow, and of the ways in which they are treated to make them 

 of use. 



7. A visit may also be paid to a convenient flour mill, beet sugar 

 factory, or other factory in which plant products are manufactured. 

 Each of the processes concerned in the transformation of the raw 

 material into its final form should be carefully observed. 



8. Materials for study may often be obtained from large con- 

 cerns manufacturing starch, sugar, cocoa, and other food products, 

 cotton seed products, or cotton cloth and other fabrics, showing the 

 stages that the plant materials have passed through in the process 

 of manufacture. 



CHAPTER XXI 



Students should bring in some of the common weeds of the 

 locality and become familiar with their general appearance. Es- 

 pecial attention should be paid in this study to the poisonous 

 weeds. If a small plot of weedy ground is available for the pur- 

 pose, the experiment may be tried of spraying it two or three times 

 at intervals of a week with a twenty per cent solution of iron sul- 

 phate. Compare the effects of this treatment on the grasses and 

 on the broad-leaved weeds. 



CHAPTER XXII 



1. The class should visit a neighboring forest or wood lot to 

 observe the different species of trees and their arrangement. Are 

 the various kinds of trees irregularly scattered or are those of each 

 sort in a group by themselves? How do the trees growing in a 

 forest differ from those of the same kind grown in the open ? What 

 is meant by " self -pruning " ? How does it come about? 



