throughout. The pectic structures were similar to those of the 

 hypodermis, except they were usually smaller and fewer. Cell walls 

 appeared to be similar in composition to those of the hypodermis. 

 When examined in sectional view in polarized light the walls were 

 highly birefringent (pi. 4, E), whereas in surface view they were 

 only weakly birefringent and showed faint crisscross striations and 

 prominent pits. 



Varietal differences in the cortex, some of which are listed in table 

 4, were small. A microscopic survey of slices cleared in the manner 



Table 4. — Histological characteristics oj the cortex from raw and 



steamed apples 





Size of cells, 1 raw 



Characters of cell walls 





Length and width 





Thickness, raw 



Flaky 











or steamed 



break- 



Variety 







Cross 

 sec- 





down 













occur- 









tional 







rence 





Range 



Average 



area 2 



Range 



Aver- 

 age 



in 14 

 steamed 

 samples 3 









Sg.fiX 











Microns 



Microns 



0.01 



Microns 



Microns 



Number 



Delicious. ._ 



172-344 X 129-241 



260 X 180 



368 



0. 9-3. 5 



1. 8 



6 



Golden De- 















licious 



198-456 X 129-258 



290 X 170 



387 



. 9-2. 6 



1. 7 



10 



Jonathan. _ 



129-413 X 129-258 



280 X 175 



385 



. 9-2. 2 



1. 6 



6 



Rome 















Beauty _ _ 



138-671 X 69-215 



270 X 150 



318 



1. 3-4. 4 



2. 



12 



Stay man 



215-430 X 172-301 



325 X 250 



638 



. 9-3. 5 



2. 2 



8 



1 Measurements of isolated cells in crush mounts of raw-fixed samples for one 

 crop year (1949). 



2 Long radius multiplied by short radius, multiplied by 3.1416. 



3 These occurrences are all minor as compared to major occurrences in hypo- 

 dermal cells. 



described by Kraus (18) revealed similarity in number and size of 

 vascular bundles. This confirms the findings of Kraus for four of 

 these varieties, Jonathan, Delicious, Rome Beauty, and Stayman. 

 Of the unstored samples, more starch granules (pi. 4, E) were observed 

 in the cortex cells of Delicious and Stayman apples than in the other 

 varieties. After 3 months of storage no variety contained appreciable 

 amounts of starch. Rome Beauty apples had smaller and Stayman 

 apples larger cells in this portion of the cortex than did the other 

 varieties. Average thickness of the cell walls was least in Jonathan 

 apples, and greater in Golden Delicious, Delicious, Rome Beauty, 

 and Stayman apples, in that order. However, because of difficulties 

 in making these measurements, it is doubtful that any significance 

 can be attached to these differences. 



Other characters of the cell walls that showed slight varietal dif- 

 ferences were intensity of stain, extent of rupture or fragmentation, 

 and the rare occurrence of birefringent bodies suggesting flaky break- 

 down. Delicious and Rome Beauty had the greatest general staining 

 capacity (least prominent pits), the least rupture, and no observed 



22 



