90 



STUDIES ON APPLES. 



The individual grains are small and vary in size from 1 to 16 microns, 

 though generally they are between -land 10 microns. Browne a found 

 the average size of the grains to be about 9 microns, but the measure- 

 ments made in the Bureau of Chemistry show that the average varies 

 widely, according to the condition of maturity of the fruit. In Table 

 IX are given the results of measurements of grains from several 

 varieties. An examination of these results will show that, generally 

 speaking, the starch grains from within the core line are smaller than 

 those from the torus flesh. In only three specimens, out of the 47 

 which were examined with this point in mind, did the reverse condition 

 occur. 



It is true, however, that in nearly ripe apples the figures might give 

 a slightly erroneous idea, inasmuch as there does not appear to be so 

 much decrease in the average size of the grains as might be expected. 

 In this connection, however, it must be remembered that the number 

 of starch grains has decreased very much, and the great majority of 

 those which figured in earlier measurements have disappeared, leaving 

 only a few stray grains behind. The smallest-sized grains which the 

 writer has been able to identify and measure are those slightly less than 

 1 micron in diameter. The writer has also occasionally found what 

 seemed to be stray starch grains remaining in apparently normal cells 

 of apples which appeared fully ripe. Such grains are rare, however, 

 and the cause for their persistence is not at all clear, though it is pos- 

 sible that it is due to a condition within the cells themselves, resulting 

 in a vitality too low to carry on the ordinary metabolic change. 



All the specimens of each variety were taken from the same orchard 

 so that the variations arising from differences in climate and soil have 

 been eliminated. 



TABLE IX. Slarch-yrain dimensions. 

 PRELIMINARY OBSERVATIONS (GROWING FRUIT). 



COMMON-STORAGE APPLES. 



"Pa. Dept. of Agr., bulletin 58. 



bThe mean diameter of the starch grains in each specimen is given, followed by the minimum and 

 maximum diameters in parenthesis; then the average of the mean diameters for all specimens exam- 

 ined on the same date is given, followed by the lowest and highest diameters found in the group. 



