274 Journal of Agricultural Research voi. xxii. no. s 



probable from the size of the fruit and the thickness and structure of the peel 

 that in fruit held at high temperatures for any considerable period there 

 would be a low oxygen pressure. This might result in some intermolecular 

 respiration and the formation of acid. At low temperatures the respira- 

 tion rate would be considerably decreased, while the rate of diffusion of 

 O2 through the tissues would not be so greatly reduced, and sufficient 

 oxygen might be present for the breaking down of the compounds used 

 in respiration of COj and HgO. A careful investigation of this point is 

 needed. The work of Gerber {4) is of interest in this connection. 



The dry weights are about the same at the conclusion of the experi- 

 ments as at the beginning. There may be a slight diminution in the 

 percentage of dry matter, but this apparently lies within the experi- 

 mental error of the determinations. The variation in thickness of peel 

 and percentage of peel is so great that thera is frequently a higher per- 

 centage of peel after the fruit has been stored four months than when it 

 was placed in storage. This is undoubtedly due to the lack of uniformity 

 in the fruits and the low percentage of shrinkage. 



The loss in weight during the four months' storage is from 3 to 4.9 per 

 cent, averaging around 4 per cent. The relative humidity of the storage 

 rooms was around 75 per cent. The fruit was not in the best condition 

 for merchandising at the end of this storage period, as it was in many 

 cases badly pitted. It is doubtful whether this method of storage would 

 be applicable to commercial conditions if the fruit were placed directly 

 in cold storage. 



EXPERIMENTS IN THE CONTROL OF PITTING 



As was mentioned in the earlier paper (7) , grapefruit tends to pit in 

 cold storage. This pitting begins as a small indentation of the skin in 

 practically any region of the surface. The sunken area gradually in- 

 creases in size, frequently becoming as much as i cm. in diameter. They 

 are usually, in the type of fruit used in these experiments, about i mm. 

 in depth. In time they may take on a brown color. This coloring occurs 

 more quickly if the fruit is removed to a warm room. These pits may be 

 very numerous on the surface of the fruit, in many cases coalescing in 

 irregular shaped patches. 



Cross sections of these pits show that they are formed by a breaking 

 down of the layer of tissue containing the oil vesicles. There is appar- 

 ently no disintegration of the tissue. The cells and vesicles simply flatten 

 out as if subjected to local pressure, the layer of tissue becoming brown. 

 The injury apparently does not extend to any distance in the spongy 

 tissue ben-ath this oil-bearing layer, and it is only after a long period that 

 any evidence of the discoloration appears on the inside of the peel. The 

 pulp of the fruit is apparently uninjured. The affected fruit, however, 

 is very unsightly, and badly pitted fruit would hardly be salable in a 

 normal market. It was evident that unless some method of preventing 



