which were to be steamed, were placed in perforated crucibles on a 

 rack in a covered kettle. Part of these specimens were steamed for 



15 minutes, and others for 45 minutes. They were then immersed 

 in FA A. All specimens were fixed in FAA for 24 hours or longer, raw- 

 fixed specimens being kept in a low-pressure chamber during the 

 first half hour and steamed-fixed specimens for a full 24 hours, in 

 order to remove all possible intercellular air or gas from the tissues. 



Dehydration and paraffin infiltration were accomplished by the 

 tertiary butyl alcohol method (17). Sections 10 microns thick were 

 cut from paraffin-embedded cubes. The stains found most helpful 

 for distinguishing cellular structures were ruthenium red and di- 

 phenylene diamine acetate. These stains, heretofore recommended 

 for use as microchemical reagents in temporary mounts (14, 17), 

 were adapted for use in permanent slides {21). 



Microchemical tests for pectic or related substances and for 

 pentosans were carried out on paraffin sections. The tests for cellulose 

 were the iodine and zinc chloride test of Artschwager {!) and the 

 sulfuric acid and iodine test described by Barrows (4) . Cellulose was 

 extracted from a few slides with cuprammonium hydroxide made as 

 directed by Shetlar (38). Some of the sections were extracted by 

 methods of Mehta (29) adapted to slides and tests applied for pectins 

 or cellulose. 



Both brightfield and polarized illumination were used in examining 

 the slides. Measurements were made with an ocular micrometer and 



16 mm., 4 mm., and 1.8 mm. objectives as needed. Photomicrographs 

 were made with Kohler brightfield illumination, and with polarized 

 illumination using a carbon arc as the light source. 



Chemical analysis 



Apples were analyzed chemically for certain constituents in order 

 to determine the relation between the chemical composition and the 

 palatability of the raw and cooked apples at each storage period of the 

 apples. Moisture, total or reducing sugars or both, total or titratable 

 acidity, and pH of the juice were determined by official methods of 

 analysis (2). Total pectin and pectic acid were determined by 

 precipitation as calcium pectate (7) . 



In each test, 20 apples were taken as the sample for analysis, 

 scrubbed with a brush in running tap water, rinsed in distilled water, 

 and dried with cheesecloth. The apples were cored, cut in half at 

 right angles to the core, and quartered by cutting again from stem 

 to blossom end. Diametrically opposite quarters were taken from 

 each apple. 



Quarters from 8 apples were grated and blended in an electric 

 blender for approximately 3 minutes. Duplicate weighed portions 

 taken for moisture determinations were dried in a vacuum oven for 

 24 hours to near constant weight. Separation of the juice from the 

 pulp was achieved by draining through prepared cheesecloth. The 

 juice was used for the determination of pH with calomel-glass elec- 

 trodes and an electronic pH meter. Titratable acidity was deter- 

 mined on 2 aliquot portions, using N/10 sodium hydroxide and the 

 indicator phenolphthalein. 



Quarters from the remaining 12 apples were used for determining 

 sugars and pectins. In order to facilitate handling, 6 quarters from 3 

 apples were taken at one time. A weighed portion of 110 grams was 



