PROBLEM 33 



61 



lowing words in the proper column on a line with the food 

 tested : none, little, much. Several pupils may work together 

 and give their results to the class so as to make the record cover 

 as many foods as possible. 



Conclusion. 1. Name five common foods rich in protein; in 

 starch ; in grape sugar ; in oil ; in water. 



2. Verify your results by comparing with food charts on pages 

 278-279 of your Civic Biology. 



A STUDY OF THE CONDITIONS NEEDED TO AWAKEN THE EMBRYO 



IN THE SEED 



Problem 33 : To show how much water is needed to make a 

 seed germinate. (Home Experiment. ) 



Materials. Soaked peas, sawdust, cups. 



Method. Pupils performing this or any other experiments 

 must remember that the success of an experiment depends upon 

 the accuracy with which it is performed and the exclusion of all 

 factors from the experiment except the one which you are trying to 

 prove. For example, in the following experiment on the effect 

 of different amounts of moisture, all the other factors tempera- 

 ture, light, food, etc. must be the same in each of the three 

 cups ; the only variable factor being moisture. Place an equal 

 amount of moist sawdust in the bottom of each of three cups. 

 Put ten soaked peas in each. Keep the seeds in one cup very wet, 

 those in the second slightly moistened, and those in the third dry. 

 Keep the cups covered in a moderately warm place. Examine 

 them daily for seven days. 



Observations. Tabulate results as follows : 



