270 Journal of Agricultural Research voi. xxii, no. s 



the season. It is evident that the proportion of peel to pulp and thick- 

 ness of the peel decrease as the fruit matures. 



A comparison of the acid and sugar changes in grapefruit in growth 

 and ripening with the acid and sugar changes of other fruits in the same 

 period of their life history brings out some interesting correlations and 

 differences. The total sugar content of deciduous fruits usually increases 

 during the growing and ripening period. This has been shown for 

 apples by Lindet, (8) Bigelow, Gore, and Howard (2), and others; for 

 pears by Ritter (12), Riviere and Bailhache (11), Magness (10), and by 

 Bigelow and Gore (i), for peaches. Numerous other investigations cor- 

 roborating this point might be mentioned. The literature pertinent to 

 this subject may be found in the works referred to here. With certain 

 vegetables a somewhat similar increase in total sugars is found. This 

 was brought out by Hasselbring (5), working with sweet potatoes, and 

 Sando (14) with tomatoes. This evidence would seem to indicate that 

 in fruits or vegetables where sugar is stored the percentage of sugar 

 calculated on a wet-weight basis increases during the growing season — 

 that is, there is not only an absolute increase but an increase in proportion 

 of sugar present as compared to the sum of the other constituents. This 

 increase in some cases is due to an increased content of reducing sugars, as 

 in the tomato, or may be due to an increase in both reducing sugars and 

 cane sugar, as in the apple, pear, and peach, or for the most part to an 

 increase in cane sugar, as in the sweet potato. 



In regard to the acid content of fruits which contain both sugar and 

 acids in appreciable quantities, there is sometimes an increase and some- 

 times a decrease in acidity as the season advances. In pears there is 

 generally a decrease. Magness (10), however, found that pears from the 

 Yakima district, Washington, and Medford district, Oregon, showed an 

 increased acidity as the season advanced. Apples, according to the 

 analyses of Lindet (8), and Bigelow, Gore, and Howard (2), exhibit a 

 decrease in acidity as the growing season advances. Peaches, on the other 

 hand, increase in acid content as they approach maturity. The decrease 

 in acidity of grapefruit during the growing season is comparable to the 

 usual behavior of the acidity in pears and in apples. 



COLD STORAGE EXPERIMENTS 



As mentioned earlier in this article, experiments on the cold storing of 

 grapefruit were carried out during the 1920-21 season. Fruit from four 

 trees was used. These trees included the two from which fruit was 

 obtained for the warm storage work, the fruit being from the lots desig- 

 nated third, fourth, and fifth picks in the experiments aheady described. 

 Not sufficient fruit was available for this work from the fifth pick from 

 tree i , so only two experiments were possible with fruit from this tree. 



Table III gives the results of analyses made at the time the fruit was 

 placed in storage and four months later. As was pointed out, because 

 of the structure of the fruit it is very difficult to obtain definite evidence 

 on the changes of the various constituents of the pulp. While the 



