INTRODUCTION. 



INTRODUCTION. 



In order to appreciate what has so far been done in the way of throwing light upon this wide- 

 spread disease of the apple and other pip-fruits, it is necessary to remember that at the outset of the 

 investigation it could still be referred to as a " mysterious disease," and there was no known method 

 of coping with it. I was appointed by the Commonwealth and State Governments of Australia for 

 the definite period of four years, for the purpose of investigating the causes of and remedy for Bitter 

 Pit a line of research very wide in its scope. 



The limited time at my disposal affected the mode of investigation to a certain extent, and 

 the breeding of new varieties of apples, for instance, combining immunity from the disease with 

 other desirable qualities, was out of the question. Besides, several of the experiments, as in the 

 testing of different stocks, were not continued sufficiently long to give definite results. However, 

 the investigation of the cause was the principal object, and this has been done, and at the same time 

 a number of experiments have been undertaken in the orchard, with a view to the control of the 

 disease. 



At first the disease was supposed to be of parasitic origin, but extended investigation failed 

 in this and other countries, to substantiate any such cause. There is now no suspicion of a Bitter Pit 

 parasite to explain or to account for the symptoms, so that we are thrown back upon the working 

 of the living organism itself, to see how the disturbance of the normal functions is brought about. 



In connection with this investigation there are three outstanding features which materially 

 aided me in bringing it to a successful issue. 



First of all, the abundance of specimens in the shape of numerous orchard trees bearing pitted 

 fruit, enabled me to carry out a series of experiments in each State of the Commonwealth. In some 

 varieties of apple, not only were the majority of the trees liable, but the individual fruits on the trees 

 were affected, sometimes to the extent of 60 or 80 per cent. Plenty of material was thus available for 

 chemical analysis, and biologic study of the disease at different stages. 



To any one engaged in special research, it is well-known that an abundant supply of suitable 

 material is a great aid to experimental investigation. In the Studies on " Cancer and Allied Subjects," 

 conducted under the Special Research Fund, at Columbia University, the programme could not in 

 some instances be carried through owing to the want of material. The bio-chemist had to acknow- 

 ledge that " Without tumourous animals, without cancer patients and without carcinomatous 

 supplies, all our plans for direct chemical attack on the cancer problem had to be suspended." I 

 was particularly fortunate in having abundance of material from six States, and often specially 

 instructive specimens from the intelligent and observant Orchard Supervisors. 



Again, it is hardly sufficiently realised even by orchardists themselves, the amount of intelligent 

 control which they can exercise over the habits and the fertility of the tree. " As the twig is bent, 

 the tree's inclined." By starting from a healthy stock and a suitable scion, the orchardist can build 

 up a tree with the height of stem, the spread of branches and the amount of wood he desires for bearing 

 the future crop. He can supply deficiencies in the soil by manuring, retain the moisture in the soil 

 by cultivation, aerate the soil by drainage, determine the number of branches and develop wood- 

 buds or fruit-buds by pruning, help pollination where necessary by growing suitable varieties beside 

 each other, and can regulate the distribution of fruit on the tree, so that each one receives its necessary 

 supplies. The action of the pruning knife in its effects upon the future of the tree, has been com- 

 pared to that of Natural Selection. Natural selection, in the words of Darwin, " preserves favoured 

 races in the struggle for Hie," and pruning, controlled by the intelligence of the orchardist, can direct 

 the growth into new channels and lead to the betterment of the fruit. 



