MAGNIFIER 



PHOTOTUBE 



Figure 11-6. Diagram Showing the Essential Components of the Cyto- 

 photometer for Absorption Measurements in the Visible Spectrum. (From 

 Swift, H., 1950. "The Desoxyribose Nucleic Acid Content of Animal Nuclei," 

 Physiol. ZooL, 23, Fig. 1, p. 171.) 



HONOCHAOtUTOfl 



CNLflRGEO IMAGE OF THE 

 CELL , PROJECTED CW THE 

 PHOTOCELL DIAPHRAGM 

 PLANE 



MEASUREMENT 

 PHOTO CURRENT 



Figure 11-7. Diagram Showing the Principle of Photoelectric Micro- 

 spectrophotometry. (From Caspersson, T, O., 1950. "Cell Growth and Cell 

 Function," W. W. Norton & Co., Inc., New York, N. Y., Fig. 4, p. 21.) 



222 / CHAPTER 11 



