90 STUDIES ON APPLES. 
The individual grains are small and vary in size from 1 to 16 microns, 
though generally they are between 4and 10 microns. Browne“ 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. 
TaBLeE IX.—Starch-grain dimensions. 
PRELIMINARY OBSERVATIONS (GROWING FRUIT). 
=A Ar. date oF i. : : = - es See 
Serial Date of | give of grains in torus Size of grains within — 
' Variety. examina- P 
. - aS b . . > 
No. rari flesh. core line.} 
1902. Microns. Microns. 
eet = York Imperial. .25 225 eC EE oe el ee ee 7. 3 (2.8 tO. 2) 6.0 (2.4 to 11.2) 
sackoee GTIMES ose = ask Sack Sore ee ee ee Ores 10. 2 (6.0 to 16.0) 6.0 (2.4 to 11. 23% 
areas | be Ey Aer > 
COMMON-STORAGE APPLES. 4 
1120 | Rhode Island Greening: - 
AS pee ut eS ee ened 5.5 (3.2 to 8.8) 2.9(1.6to 6.4) 
Bie sm = FSET aoe se mel hee don. 6.0 (2.4 to 9.6) 4.2(1.6to 8.0) 
ES is te My Se eae CPR SS | ae do 4.9(1.6to 9.6) 4.2(1.6to 8.0)7 
LD SR Se AL Se eee. eee t sf ee do 4.2(1.6to 9.6) | 3.1(0.8to 6.4% 
A VONR OG. oe 0G oe ao 8 i Sh ee 5.1(1.6to 9.6) 3.6(0.8 to 8. 0) 
a Pa. Dept. of Agr., bulletin 5s. - 
6The 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. 
