VITAL GROWTH AND CRYSTALLIZATION 



43 



through fine openings. X-rays have a wave length only 

 one ten-thousandth as long as that of ordinary light. To 

 produce a like result they must pass through infinitesimal 

 openings, so fine that they cannot be made artificially. 

 However, nature itself provides us with such fine openings: 

 they are found in the crystals. The appearance of the dots 



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i • » . 



• • # t 



L 



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Fig. 24. Appearance of X-Rays after Passing through a Crystal 



The large dark patch in the center is produced by the bulk of the ray 

 which passes straight through the crystals. Surrounding this central ray 

 there appears a large number of smaller dots distributed regularly around 

 it. Their appearance is an unmistakable indication of crystallinity. 

 (Courtesy, Dr. O. Glasser, Cleveland Clinic.) 



on the plate indicates that the crystal contains an exceed- 

 ingly fine grating. The regularity of the pattern formed by 

 these dots points to the symmetry of the infinitesimally fine 

 structure of which the crystal consists. 



A similar symmetrical pattern indicates that crystallinity 



