6i 



FIG> 47- Crude test for nearsightedness and far- 

 sightedness. 



EXPERIMENT 49. A TEST FOR SIGHT 



The following is a very superficial test for vision. 

 (a) The normal | ^ ^^ ^^^^ 

 eye is able to read ^^^r W*^ 



typeofthesizeshown Mi 

 in Figure 47 at a dis- 

 tance of 1 6 feet. By 

 means of the printed letters (Fig. 47) examine your own eyes 



and determine if they are 

 normal. 



What is nearsightedness ? 

 What is farsightedness? 

 Explain how each can 

 be remedied by the use of 

 glasses. 



(b) Test your eyes for as- 

 tigmatism by means of a 

 card having lines of the 

 same brilliancy radiating 

 from the center. Astigma- 

 tism is present if some of the lines are brighter and more 

 distinct than others. 



FIG. 48.-Tes, (or astigmatism. 



EXPERIMENT 50. LIGHT AND ITS EFFECT ON MICRO- 

 ORGANISMS 



To ten teaspoonfuls of water add one spoonful of 

 molasses, mixing the liquids thoroughly. Rub a little 

 compressed yeast in a small amount of water, and put 

 a few drops of this into the molasses water mixture. 



Divide the solution of water-molasses-yeast * into two 



