Figure 11-14. Dark (a) and Bright (b) Phase-Contrast Micrographs of 

 Living, Unstained Sperm Cells. (From Richards, O. W., 1946. "Biological 

 Phase Microscopy," Cold Spring Harbor Symp. Quant. Biol., 11, Figs. 20 

 and 21. Courtesy of Dr. O. W. Richards, American Optical Company, Re- 

 search Department, Southbridge, Mass.) 



232 / CHAPTER 11 



