20 Alfred J. Eivavt: 



been heavily sprayed for some time than in orchards which have- 

 been lightly sprayed or not sprayed at all. It is unfortunate that 

 statistics on this point, which by now should have been available in 

 abundance have not been published. It is quite beside the point to 

 indicate the existence of bitter pit in unsprayed orchards as a com- 

 plete and satisfactory answer. If bitter pit is simply the result of 

 local oligodynamic poisoning, any trace of any poison capable of 

 absorption may produce it, independently of how it is absorljed and 

 whether it is originally present in the soil or not. 



The Browning of Bitter Pit Tissue. — In certain varieties of 

 apples, notably Statesman, the pit tissue is usually paler than in 

 other varieties. The browning is due to the action of the oxidase 

 liberated from the dying j^rotoplasm upon the tannic acid of the 

 cell sap. When a Statesman apple is cut, the cut surface remains 

 paler than in most apples, the browning being most evident along 

 the veins. This might be due either to a deficiency of oxidase or of 

 tannin or to the i^resence of an oxidase inhibiter. More than one- 

 distinct variety of ajople has been known as Statesman. One of 

 these false Statesmans is known as Chandler's Seedling. Its pulp 

 browns readily Avhen cut. The sap was expressed from equally ripe- 

 true Statesman and from Chandler's Seedling and tested for tannic 

 acid; the former yielded 0.24 and the latter 0.16, a difference which 

 is hardly sufficient to explain the pronounced difference of browning. 



Testing with guiacum and peroxide of hydrogen for oxidase gave 

 about the same depth of blue, but this test though a delicate one 

 does not discriminate quantitively. A dilute solution of amidol 

 is a good test for apple oxidase. By adding varying quantities of 

 apple sap until the rate of change of colour was the same in each 

 case, it Avas found that three parts of Chandler sap contained as 

 nuich oxidase as 8 parts of Statesman sap. The glycerine extract 

 from pulp dried by pressure gave values of 3 and 9 respectively. 

 No evidence of the presence of any special inhibiting agent could 

 be obtained, so that the feeble browning of Statesman pulp is 

 mainly due to a deficiency of oxidase. The amount of oxidase pre- 

 sent in an apple can therefore to some extent be used as a test to 

 distino-uish between certain varieties. 



