THE NATURE OF THE VARIETY PREDISPOSITION AND IMMUNITY. 27 



In the matter of the amount of juice in the fruit, for instance, ripe specimens from different 

 orchards showed sometimes a greater amount of juice in Cleopatra and sometimes in Yates during the 

 past season. In the previous season specimens taken from the same, orchard showed a greater amount 

 of juice in Yates than in Cleopatra, so that this factor varies in different seasons and even in the same 

 season. 



In the young wood of Yates, analysis showed a much higher percentage of phosphoric acid 

 and magnesia, as compared with that of Cleopatra, but these are only the results for a single season. 

 From the practical point of view these chemical differences cannot be controlled by the orchardist, 

 but they may throw light upon the hidden causes which influence the development of Bitter Pit. 



In order to determine the differences, if any, in the minute structure of the wood, as regards 

 the vessels of Cleopatra and Yates, I selected one, two, and three-year-old wood of each, bearing 

 fruit-buds, from the Burnley Horticultural Gardens. Numerous transverse sections were made, 

 and as the medullary rays radiating from the pith to the cortex are very regularly distributed I was 

 thereby enabled to count the number of the vessels, bounded on each side by the medullary rays. 



At the same time their diameter was carefully measured in micro-millimeters or microns, 

 which are approximately ^ s ^u f an inch, and as the shape is somewhat oval, the longer and 

 shorter diameter was determined. The average number and diameter of the tubes is shown in the 

 following table, but the length of the tubes is not taken into account. 



TABLE XIV. AVERAGE NUMBER OF TUBES BETWEEN THE MEDULLARY RAYS AND THEIR DIAMETER 



IN CLEOPATRA AND YATES RESPECTIVELY. 



Number of Tubes. Diameter of Tubes. 





Cleopatra. Yates. Cleopatra. Yates. 



One-year-old wood . . 18 18 26 x 21 33 x 25 



Two-year-old wood 27 27 32 x 23 31 x 29 



Three-year-old wood 45 61 34 x 25 34 x 28 



An increase in the number of tubes is only shown in the three-year-old wood of Yates, and the 

 difference in diameter is not great, but on the whole it is in favour of Yates. Taking the results of a 

 single season, the larger number of tubes and their greater diameter in Yates will allow a freer flow of 

 sap, and if this ensures a more regular supply of nourishment to the growing fruit it will tend to 

 reduce the liability of Pit. 



In a constitutional disease such as this, there is an evident possibility of starting from an 

 immune stock, and this may either be obtained by crossing or from a chance seedling. I have already 

 crossed immune Yates with susceptible Cleopatra, the object being to get the size and quality of 

 Cleopatra combined with the immunity from Pit of the Yates. This is necessarily slow work, but 

 once the proper strain has been secured, it can be multiplied indefinitely. 



A seedling apple tree, supposed to be from the Irish Mother, has been raised and grown by 

 Mr. W. McKeown, at his Glenone Orchard, Dromana. It has been named " Glenone" by Mr. E. E. 

 Pescott, and bears large and beautifully-marked fruit with a delightful aroma, and is so far free from 

 Bitter Pit (Frontispiece). It was grafted on to a Ben Davis stock, and came into bearing in 1911. 

 This season it produced between 4 and 5 bushels of fruit, which ripened early in March, and is suit- 

 able for both culinary and dessert purposes. 



A cross between Cleopatra and Rome Beauty has already been referred to, raised by Mr. Robin, 

 of Nuriootpa, and named " Clerome." It is considered to resist Pit as well as its seed-parent, Rome 

 Beauty, in- that district. By the above means a disease-resisting variety may be reared of commercial 

 value, and since there is no question of a parasite being concerned in this disease, there is no danger of 

 a complication arising from breeding adapted races of the pest at the same time. 



