18 



BITTER PIT INVESTIGATION'. 



Some Rymer apples affected with frost were carefully examined. A freezing of the calyx 

 end shortly after the fruit had set caused the deformity, and they had afterwards grown almost to 

 their full size, and many of them had taken on their natural colour. When a transverse section is 

 made, streaks of brown tissue are seen in the flesh about a quarter of an inch beneath the skin on 

 the affected side, and these are more sparingly distributed on the swollen side. Wherever these 

 streaks occur, there is a sort of natural parting in the flesh, and when a small portion of the brown 

 collapsed cells is examined microscopically, there are invariably found numerous tufts of the 

 colorless hair-like structures afterwards referred to. The cells composing them still contain starch 

 grains, as they are coloured blue by iodine, and they are quite similar to the cells of the flesh, only 

 much smaller, and arranged in the form of filaments. 



VIII. — ££ WOOLLY STKIPE" OF SEED VESSELS, AND A SIMILAR 

 DEVELOPMENT IN THE FLESH OF THE APPLE. 



When an apple is cut transversely about the middle, each of the five seed-vessels constituting 

 the " core " is seen to have a cleft formed by the splitting of the carpels, and this is usually fringed 

 with a white woolly substance. On examination under the microscope this is seen to consist of 

 numerous colorless, jointed, wavy, branched filaments, the cells of which are cylindrical in shape, the 

 terminal cells rounded at the apex, and the cell-walls finely warted. They occur where the 

 rupture has taken place, and the outgrowths are the result of it. 



Not only are these branching filamentous structures found in the clefts of the carpels, but 

 the inner face of the firm cartilaginous wall bounding the seed cavity has often definite streaks or 

 bands of the same filamentous structures projecting into the cavity, and these stripes have been 

 named by Sorauer (85) from their characteristic appearance " Woolly Stripes " (Wollstreifen) 

 The inner wall itself is composed of more or less elongated * thick- walled cells, with numerous pore- 

 canals, and underlying that are layers of polygonal thick-walled cells which pass into ordinary 

 parenchymatous tissue (Fig. 52). This structure evidently gives the necessary firmness to the walls 

 of the seed vessels, and at the same time acts as a protection against the entrance of fungi, which 

 might reach the cavity in those cases where there is a hollow space leading from the " eye " end of 

 the apple. 



Sorauer considers, and justly so, that where the woolly stripes occur, this protection against 

 fungi reaching the flesh no longer exists, since the woolly hair-like structures gradually pass into 

 the cells of the flesh (Fig. 52). He concludes, therefore, that at the time when the greatest swelling 

 of the fruit takes place, such a tension is produced in the cells by the sudden absorption of relatively 

 large quantities of water, that the cartilaginous wall is ruptured along the lines corresponding to 

 the stripes and the inner thin-walled cells, relieved from the pressure, grow out into the cavity in 

 the form of elongated jointed filaments. Here, again, the filamentous structures are produced as 

 the result of rupture. But these self-same structures are not confined to the seed-vessels, for they 

 occur as well in the flesh of apples which have been bruised and those injured by hail or frost, and 

 even in association with the brown patches of Bitter Pit. 



A Yates apple was artificially bruised, and, in connexion with the broken, collapsed, and 

 discolored tissue, there were numerous tufts of the filamentous cell-rows. 



When the injury was produced by hail, and the skin either broken or unbroken, the same 

 filamentous cell-rows were found associated with the bruised and discolored tissue, In apples 

 struck by frost, the brown patches in the interior were surrounded by numerous tufts of filaments 

 and even in the brown spots of Bitter Pit there was an occasional development in the adjoining cells 

 of similar structures. 



