I2O MARGARET REED LEWIS AND WM. REES B. ROBERTSON. 



PLATE III. 



FIGS. 21, 22, 23. Unstained. Division stages drawn to show mitochondria 

 before the action of acetic acid. Zeiss 8 oc. 2 mm. lens. 



FIGS. 24, 25, 26. Same cells after acetic acid fumes. Mitochondria have disap- 

 peared and the cytoplasm is coagulated. Spindle fibers can now be seen. 



FIGS. 27, 28, 29. Unstained. The fusion of two cells to form a single double 

 cell with two groups of chromosomes and two masses of mitochondria. Leitz 

 Binoc. 4b X 1/12 lens. Chromosomes not all shown. 



