208 PICTURING MIRACLES 



scopial work the necessity of much experimental 

 work is to emphasize certain parts of a subject to 

 make them more definite on the screen. This means 

 using the kind of light that will give the desired re- 

 sult. As light is waves of energy, the length of the 

 wave will give one result and a longer or shorter 

 wave still another. So one is justified in choosing the 

 wave giving the desired result, or to eliminate some 

 waves and allow only others to illuminate the sub- 

 ject. By stopping all the horizontal waves and allow- 

 ing only the vertical ones to pass we have what is 

 called polarized light. Some of the results from using 

 it are most remarkable, although it is a new tool 

 and not enough work has been done in color to say 

 just what advantages it has or what it will show. It 

 has opened the door for many new discoveries. In 

 plant or animal tissue the cell walls show up much 

 more clearly than in direct or dark field lighting, 

 while possible other parts of the cell will show not 

 as clearly, although that is still an unsettled question. 

 One short picture I made last summer showed 

 very definitely that protoplasm does pass from one 

 cell to another, which is still a disputed question 

 with biologists. Crystals forming in a drop of water 

 as the water evaporates and viewed with polarized 

 light are the most beautiful objects I have ever seen; 

 all the colors of the spectrum shoot across the drop, 



