DISCUSSION OF ZIRKLE'S AND TOBIAS' PAPERS 



391 



Fig. 5. Section of G-min-irradiated epidermis, stained with neutral red in tap water 



with a pH of 7.4. There is uniform storing of dye in the unaffected cells, while the 



damaged cells have marked concentration of dye in the areas of disturbed cytoplasm. 



These "spots" under the ordinary microscope are cherry-red. 



Fig. 6. Same section as above, but it now has been titrated with 1/50 N NaOH 



solution. The neutral red is precipitated out of solution and migrates to the injured 



areas to form needle-like crystals. 



