CHANGES IN COMPOSITION DURING GROWTH. 7 



II. CHANGES IN CHEMICAL COMPOSITION OF THE PEACH DUB- 

 ING GROWTH AND RIPENING. 



The definite stages in the development of the fruit selected for 

 sampling were as follows: 



(1) After the June drop. This period of the life history of the peach 

 was selected as the first time of sampling because of the fact that it is 

 the earliest point at which a sample can be secured of the fruit that 

 will probably mature normally. The fruits which are not going to 

 mature on account of imperfect fertilization or other cause "shatter" 

 or drop off at this time. Before securing the first sample the trees 

 were shaken and a portion of the fruit which appeared to be firmly 

 attached, selected from different sections of the tree, was picked. 



(2) When the stone hardens. The peaches were carefully watched 

 until the time when the stone could only be cut through with difficulty 

 with a knife. The second sample of peaches was then secured. 



(3) When market ripe. Here the fruit is fully developed and almost 

 the full degree of color has been attained. 'The flesh, however, is firm 

 and the fruit will stand shipping. This is the commercial picking 

 time. 



(4) When fully ripe. Here the peach is fully colored and somewhat 

 larger than at the time of market ripeness. The flesh is soft and the 

 fruit so easily bruised by handling that it will not stand shipment. 



The examinations made in the Bureau of Chemistry were performed 

 at three, and when possible at four, intervals of the life history of the 

 peach. In selecting all the samples the fruits were gathered from all 

 sides of the tree and from the inner as well as the outer portions. The 

 successive samples of each variety were taken from the same tree. An 

 attempt was made to secure a sample of such size that its composition 

 would represent the composition of the average peach upon the tree 

 at that time. Of the first samples picked about a hundred peaches 

 were employed. Of the last samples, when the peach was fully ripe, 

 about twenty peaches of each variety were secured for each sample. 

 The fruit was gathered by one of the writers on the morning of the 

 same day on which the analysis was begun. 



The varieties of peaches employed were Triumph, Rivers (or Early 

 Rivers), Early Crawford, Stump (or Stump the World), Elberta, 

 Orange Smock, and Heath Cling (or White Heath). The following 

 descriptions of the several varieties were furnished by Mr. W. A. 

 Taylor, of the Bureau of Plant Industry: 



TRIUMPH. 



Size medium; flattened, globular, often angular. Surface uneven; greenish yellow, 

 washed with mixed red and marked with vivid broken stripes of dark purplish red; 

 dots rare, pink; down very abundant, short, loose; cavity wide, oval, deep, abrupt, 

 pink; suture generally shallow, extending from cavity to apex; apex a sharp point 

 extending above suture walls; skin thick and leathery, but soft; stone of medium 



