34 



BITTER PIT INVESTIGATION. 



Special attention was also given to the period when Bitter Pit was first observed in the 

 different varieties, and, since they vary so much in their relative stages of growth and as the date 

 would not convey a correct idea of their age, I have designated the time according to the stage of 

 ripening. What constitutes ripeness has not been definitely settled in a practical way, but we 

 have to distinguish between the ripening which takes place upon the tree and to which it contributes, 

 and the maturing which occurs after picking, and is generally spoken of as after-ripening. In 

 ripening then the fruit is brought to its full size and development through the activity of the 

 parent-tree, and in after-ripening the fruit is dependent on its own resources. 



This list of varieties with their relative susceptibility to Bitter Pit will be recorded each year 

 on similar lines, together with any new varieties which may develop it. The result will be that at 

 the end of the investigation the liable varieties will be more or less definitely determined. With 

 such a severe test for susceptibility to this disease, a number of promising Australian seedlings 

 and varieties not generally known may be found worthy of being brought into general 

 cultivation. 



XII.— THE GENERAL STRUCTURE OF THE APPLE AND PEAR, 



The apple and pear are what are known as " pip " fruits, and, since they possess a special 

 structure which distinguishes them from ordinary fruits, they have received the technical name 

 of pome. Wherein this peculiarity consists and which has an important bearing on the susceptibility 

 of such fruits to Bitter Pit and kindred diseases, will now be considered. 



The apple is attached to the end of the parent-branch by a longer or shorter stalk, through 

 which the necessary nourishment is conveyed to it ; and if a section lengthwise and crosswise is 

 made of the fruit, as in Figs. 69 and 71, the essential parts will be shown. The apple, unlike other 

 normal fruits, does not merely consist of seeds enclosed in a case, but surrounding that case there 

 is the " flesh " of the apple. If we glance at the flower before the fruit is developed, there is seen 

 at the centre of it a five-chambered ovary, and each chamber encloses normally two ovules. After 

 fertilization, the ovules become the " pips " or seeds, so that there are now five carpels or seed-vessels, 

 constituting the true fruit, with thick fleshy walls, but the inner face of each, bounding the 

 seed-cavity, is smooth, firm, and cartilaginous in texture. 



The five carpels enclosing the seeds constitute what is known as the " core " of the apple, 

 and this represents the true fruit or the mature and fertilized portion. Surrounding the core there 

 is the flesh covered by the skin, and this is superadded in order to enhance the attractiveness of the 

 fruit and increase the chances of the distribution of the seeds. 



While the core is undoubtedly represented by the five carpels, there is a conflict of opinion 

 as to the origin of the flesh, but it is generally considered to be the enlarged and succulent receptacle 

 or top of the flower-stalk investing the core. A pomaceous fruit, therefore, consists of an edible 

 portion and a seed-bearing portion, and, while the seed-bearing portion is the true fruit, the edible 

 portion is simply added to render the whole attractive, and when eaten by animals, to insure the 

 deposition of the seeds under suitable conditions for germination. 



_ The object of the grower is to produce " flesh," and not " seed," which is a drain upon the 

 vitality of the tree, and there are some " seedless " apples now under cultivation. 



The pear in its essential structure agrees with the apple, but differs in detail (Figs. 78, 79). 

 The configuration is different, for there is an elongated tapering fleshv portion towards the 'stalk 

 end, so that the core is towards the crown. It also differs from the apple in containing groups of 

 what are known as " stone-cells " scattered through the flesh, constituting the " grit " of the pear. 

 These will be more fully cousidered in connexion with the skeleton. 



