Bitter Pit in Apples. 415 



other words, any poisons present in the pit tissue are the cause 

 of the pit and not the result of it. 



The source of the poisons causing bittep pit. 



None of the vohitile poisons tested appear to be likely causes 

 of bitter pit under natural conditions, and their action would 

 not suffice to explain the permanent character of the poisoning 

 and its localised origin. Nor do apples appear to have any 

 power of autotoxication sufticient to explain the symptoms 

 observed, although they do produce, when young, traces of 

 formaldehyde, which is a poison in excess, but only a relatively 

 feeble one. Its action would, however, be a generalised and a 

 rapidly spreading one, and the tests quoted above showed that 

 it was from oOOO to 300,000 times less poisonous to apples than 

 copper and mercury salts, and, in fact, less poisonous to apples 

 than any of the other poisons tested, with the exception of 

 ammonia and lime water. Evidently, therefore, the poison must 

 be derived from outside the plant, either (1) directly through 

 spray poisons applied to the surface, or (2) by poisons absorbed 

 from the soil through the roots. 



The bitter pits starting from the surface usually beneath' 

 lenticels are largely due to the entry of spray poisons. If the 

 development takes place late, when the apples are adult, the 

 pit tissue will contain no starch grains, and the same is the case 

 when pits are formed in very young apples. The action: of the 

 poison is not to cause the condensation of starch grains, but 

 their non-solution during ripening. Nearly every apple, even 

 if apparently sound, has a few cells in which the requisite toxic 

 concentration has been reached to do this. Such cells only die 

 when either the concentration increases as the result of the 

 continued flow of sap and the evaporation of the surplus 

 water, or when the resistance of the cells with increasing age 

 falls to the toxic limit. This incipient bitter pit which appears 

 to be almost always present in apples, is certainly the result of 

 the absorption of poisons from the soil, and certain food ele- 

 ments (Ca, Mg, K) are capable of acting as poisons when they 

 are not present in their appropriate relative concentrations. The 

 complete and permanent localised arrest of ferment action can 



