Photomicrographs of hypodermal and cortical cells, before and after cooking;. 

 All except D were made with polarized light. A, Rome Beauty raw, hypodermis 

 treated with ammonium oxalate, tested for cellulose with iodine and zinc 

 chloride; B, Rome Beauty steamed for 45 minutes, hypodermis treated with 

 ammonium oxalate, stained with ruthenium red; C, Rome Beauty steamed for 

 45 minutes, borderline cells between hypodermis and cortex, treated as in 

 figure A; D, Golden Delicious steamed for 45 minutes, hypodermis treated with 

 4 percent sodium hydroxide and tested for cellulose with iodine and sulfuric 

 acid, as seen in brightfield illumination; E, Delicious unstored sample raw, 

 cortex cells containing starch grains; F, Delicious unstored sample boiled for 

 8 minutes, cortex cells containing starch grains, a, Intercellular space; b, pit 

 area; c, brown-stained pellicle seen surrounding cells after removal of pectins; 

 d, middle lamella; e, cell walls showing flaky breakdown; /, starch. X 345. 



