Cuticle thickness, determined for all samples, was found to range 

 from 8 to 30 microns (table 2) . Stayman apple cuticle had the great- 

 est range (12 to 30 microns), that from Delicious and Rome Beauty 

 apples the next greatest (8 to 20 and 12 to 24 microns), and that from 

 Golden Delicious and Jonathan apples somewhat less (10 to 20 

 microns). When cuticle measurements were averaged by variety, the 

 highest average (18.1 microns for Rome Beauty) was only 4.1 microns 

 greater than the lowest (14.0 microns for Jonathan). Measurements 

 for Stayman, Golden Delicious, and Delicious intervened in decreasing 

 order. 



Cuticle from stored samples averaged slightly thicker than that 

 from unstored samples. No other differences between the two lots of 

 samples were observed. 



As has been shown (5, 6, 30, J+5), many varieties of apples are subject 

 to cracking and replacement of some of the cuticle by suberized 

 (corky) areas called russet. Although cork is usually classified as a 

 waterproof tissue, it was reported (34) that the presence of these corky 

 areas on apples means a lowered water retention capacity in the skin. 

 In this study, interruptions in the surface of the cuticle occurred in 

 the form of breaks, slits or channels, and eroded areas as well as russet 

 (fig. 2, table 2). Internal interruptions in the cuticle were also ob- 

 served in the form of spongy areas and cavitylike structures. Chan- 

 nels were common in all varieties. The cuticle of Golden Delicious 

 apples (pis. 1, C; 2, D) was most subject to russet and other surface 

 interruptions, and was most spongy or least homogeneous internally. 

 Jonathan apples were intermediate in the amount of russet ; Jonathan 

 cuticle was the least spongy internally but had numerous slits or 

 channels (pis. 1, D, E; 2, E). Cuticle of Delicious and Rome Beauty 

 apples (pis. 1, A f By F, G; 2, A, B; 3, A, B) had the smoothest or the 

 least interrupted exterior surface of all and was more homogeneous 

 internally than that of Golden Delicious apples. Stayman apples were 

 high in russet and sponginess and intermediate in the number of 

 surface interruptions in the cuticle (pis. 1, H, I; 3, C, D). 



Supplementary cutin deposits were observed in the walls between 

 the epidermal and hypodermal cells of all the varieties except Jona- 

 than. They were confined to walls between epidermal cells in Rome 

 Beauty apples, while in Stayman, Golden Delicious, and Delicious 

 apples they occurred in walls of the hypodermis, 1-, 2-, and 3-cell 

 layers deep. These deposits may have been a factor involved in 

 toughness of skin, in determining storage life of the apples, and in 

 adherence of skin to flesh in baked apples. 



The cuticle was colorless in sections stained with ruthenium red, 

 except for pink veins and films extending horizontally near the outer 

 walls of the epidermal cells, and radially toward the surface; these pink 

 structures possibly represent concentrations of pectic materials. 



When stained by the diphenylene diamine acetate procedure, the 

 cuticle was seen to consist of an outer and an inner zone of dark and 

 light olive to tan color, respectively (pis. 2, A, C, E; 3, A, C); the 

 veins and films were dark brown. The cuticle usually appeared layered 

 or striated or both in these preparations. 



After having been steamed, the cuticle showed reduced capacity to 

 stain with diphenylene diamine acetate, especially in the outer zone 

 (pis. 1, B, E, G, I; 2, D, F; 3, B, D). The cuticle of the Rome Beauty 

 variety snowed an increase in the number of channels (pi. 3, B). No 

 other alterations were noted attributable to cooking. 



18 



