26 BITTER PIT INVESTIGATION. 



It has already been remarked that the Yates apple, from its size and shape and general char- 

 acters, is more nearly allied to the Crab than Cleopatra is, and the smooth under surface of the leaf 

 will allow of transpiration to take place more freely and thus tend to prevent excessive transpiration 



by the fruit. 



In the original Wild or Crab apple in Britain, the leaves are either smooth underneath or 

 downy when young, and De Candolle notes in his " Origin of Cultivated Plants," that there are two 

 varieties wild in Germany, the one with smooth leaves and ovaries, and the other with leaves downy 



underneath. 



This division into smooth and downy leaves suggested that a more extended examination of 

 varieties might be made, and since there are between six and seven hundred apple varieties in the 

 Burnley Horticultural Gardens a census was taken of the nature of the leaves in each case. 



It was only among the Crabs that the leaves were decidedly smooth on the under surface, and 

 of these only the following eight : 



American Cherry. Large Red Siberian Crab. 



Barry. Transcendent. 



Darling. Virginian Crab. 



Dean (Double Flowering). Yellow Siberian Crab. 



This hairy covering is practically absent in the Yates, in common with many of the Crab 

 apples, and in correlation with this, the Yates is much less drought-resistant than the Cleopatra. 

 The Yates is usually planted in the valley for moisture, owing to its susceptibility to drought, and 

 since this variety is apt to bear a large crop of undersized fruit, the necessity for a good supply of 

 water' is apparent. 



IV. THE NATURE OF THE VARIETY PREDISPOSITION 



AND IMMUNITY. 



It is a matter of common experience that particular varieties of apple are more subject to 

 Bitter Pit than others grown in the same orchard, also that a variety may be badly affected in one 

 locality and comparatively free in another. This predisposition to or immunity from the disease 

 evidently depends on some factors in the plant itself, or is due to the action of the environment. 



An attempt was made to determine some of these factors by comparing a non-liable variety 

 such as Yates with a liable variety such as Cleopatra. From its size and shape and general characters, 

 the Yates was considered to be more nearly allied to the Crab apple than Cleopatra, and the Crab 

 itself is immune. In fact the tendency to Bitter Pit is inherent more or less in the very constitution 

 of the cultivated apple, whether grown in Australia, or at the antipodes of Australia, in Britain. 

 Bitter Pit is a functional disorder, in which the vascular system or conducting tissue is largely con- 

 cerned, and the cultivated apple has in a great measure lost the hardy nature of its ancestors. 



The Crab apple is small and sour, and only on an average one inch in diameter. It is so called 

 on account of its sour biting taste like the nip of a crab. As soon as our ancestors began to improve 

 it, and enlarge it, and make it more succulent and sweet, the vascular system or stringy material was 

 interfered with; it was reduced relatively to the size of the fruit, and a softening of the fibre occurred. 

 As a consequence, there is a delicacy of constitution introduced and a feebleness in the power of the 

 rapid transport of food materials, so that we have to counteract this tendency to a weak conducting 

 system by appropriate methods of treatment. 



In seeking to determine important points of difference between Cleopatra and Yates, which 

 might possibly explain their different behaviour towards Bitter Pit, it is necessary to extend the 

 observations or experiments over several seasons, and obtain results in different districts. 



