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THE AMERICAN NATURALIST [Vol. XLVIII 



The different lots of a variety may differ considerably in 

 specific gravity, though a s a rule running somewhat close 

 together, thus Ben Davis and Gano are apples of low spe- 

 cific gravity, while Grimes, Stayman, Wagener, and Yellow 

 Newtown run rather high and Baldwin and Home may be 

 classed as medium in this respect. Overgrown apples 

 were low in specific gravity, probably owing to more air 

 space between the cells. This is more apparent upon 

 examining the results for individual apples than upon 

 comparing the average for different lots, as in the latter 

 case the extremes are modified by averaging with the re- 

 sults for more normal specimens. On the other hand r 

 small and rather undeveloped apples are apt to have a 

 high specific gravity on account of their solid flesh and 

 usually closed core. Juicy apples, if not overgrown, have 

 a high specific gravity when the juiciness is due to a high 

 moisture content. 



The relation of specific gravity to keeping quality is of 

 interest. While some late keeping varieties have nor- 

 mally a low specific gravity, those lots of a given variety 

 having a high specific gravity for the variety are usually 

 the best keepers. This is in line with the fact that certain 

 causes which give rise to fruit of poor keeping quality 

 also produce a low specific gravity. This is shown very 

 strikingly by a comparison of the specific gravities as cal- 

 culated month by month through the season. As the 

 calculations were made at the time the fruit was found 

 fit for use, the monthly averages show the steady increase 

 in specific gravity with the better keeping quality of the 

 fruit, though modified somewhat by the peculiarities of 

 the different varieties which happened to be in season at 

 different times. These averages are as follows : Novem- 

 ber and December, 0.787; January, 0.787; February, 

 0.810; March, 0.831; April, 0.852. Though these results 

 may seem to be at variance with I toward 's observations 

 it is possible that if the same specimens had been tested 

 at intervals a decrease in specific gravity would have 

 been noted. 



Chemical Composition.— In order to throw some light, 



