GENERAL SUMMARY. 65 



STRUCTURE OF THE APPLE. 



In order to understand and thoroughly appreciate the abnormal or diseased condition, we must 

 first become acquainted with the normal or healthy condition of the organism or organ with which 

 we are concerned. The structure of the apple and pear has been carefully and minutely studied, 

 both in their early and later stages in the three-fold aspect of the skin, the flesh, and the core, together 

 with the conducting vessels which ramify and interlace throughout. 



The parts immediately concerned are the pulp-cells, constituting the flesh, and the vessels which 

 bind and nourish them. 



The pulp-cells are relatively large, bladder-like, thin-walled structures, and in the growing season 

 are filled with starch grains. This portion of the fruit increases in size, not so much in the develop- 

 ment of new cells as in the enlargement of those already existing, and it can readily be understood that 

 when approaching maturity they are in a high state of tension. 



The sap can pass from cell to cell by the slow process of diffusion, but this process has to be 

 accelerated, and it is done by means of a wonderful system of conducting vessels so well distributed 

 that the nutritive fluid is conveyed to the most distant parts. The vessels enter the fruit in the form 

 of bundles or strings through the stalk. The ten bundles from (ho stalk spread out in the flesh like 

 the ribs of an umbrella, and come together again at the "eye" end of the fruit. From these ten main 

 bundles branches pass inwardly to supply the core and outwardly to supply all the parts outside the 

 core. 



CONTINUOUS NETWORK OF VESSELS. 



The apple in the growing season is constantly expanding, and it has to solve the problem of 

 continually adjusting its vascular or supply system to the requirements of the various parts. The 

 critical part is at the circumference of the flesh, where the growth is necessarily greatest, and the 

 difficult}' is met by a process of wondrous beauty and efficiency. Between the skin and the flesh the 

 vessels spread out so as to form a continuous network, and from the definite meshes of this net tufts of 

 vasculars arise to supply the skin. This network is developed in the earliest stages of the formation 

 of the apple, so that it has to keep pace with the growth of the apple, just as the growth of the human 

 skull-cap has to keep pace with the expanding brain. The position and nature of this continuous 

 network has a most important bearing upon the origin of Bitter Pit, and throws fresh light upon this 

 hitherto mysterious disease, as we have already seen. 



MANURIAL EXPERIMENTS. 



The action of fertilizers, both as regards yield and Pit, was found to vary with the nature of the 

 soil and the climatic conditions. In Victoria the highest yield was obtained with a complete manure, 

 such as superphosphate, sulphate of potash, and sulphate of ammonia, and it was practically the same 

 when kainit replaced sulphate of potash. In South Australia the complete manure required the 

 addition of lime to secure this result, and in New South Wales a highly increased yield over the 

 unmanured plots was obtained with superphosphate, sulphate of potash, and ground limestone. In 

 Western Australia superphosphate and sulphate of potash, without the addition of lime, gave more 

 than a fourfold increase over the check plots. 



These different results are no doubt chiefly due to differences in the soils under experiment, 

 along with the varying ages of the trees, and cannot, of course, be held to afford general guidance as 

 to the most effective methods of manuring in the respective States. 



As regards Pit, the smallest amount occurred in Victoria when bonedust was added to a complete 

 manure, and there was not a great difference in that associated with the highest yield. In New South 

 Wales the least amount of Pit was also associated with the highest yield, being less than one-half 

 per cent. In South Australia, on the other hand, the least amount of Pit was in the plot with the 



