174 



of water must lead to a perceptible pressure and also some thickening of the fruit- 

 wall. This must promote the opening of the fruit as well as the remarkable de- 

 taching of the stone, although the required mechanical power for these processes 

 must, no doubt, chiefly be the tension of the tissue of the parenchyma of the fruit- 

 wall existing independently of the gummosis. Finally the stone is found quite loose 

 within the fleshy shell, which mostly opens like a bivalvate mollusk, but sometimes 

 shows three or four fractures. The vascular bundles, which pass from the fruit- 



-' t,' 



Fig. 2 (3). Gum canals in the 

 transverse section of thefruit- 

 flesh of a peachalmond: ha 

 hairs on epidermis; hw der- 

 moidal tissue; b/>chlorophyll- 

 parenchyma; xl xylem bund- 

 les; ph phloem bundles; gp 

 gum canals sprung from 

 phloem bundles. 



Fig. 2 and 3 are reproductions 

 from my above mentioned 

 treatises of 1883 and 1886. 



flesh into the stone, are thereby torn off clear from the stone. At the base the 

 separation seems provided for by an intercepting layer, as at the fall of leaves. 



The portion of the phloem bundles within the stone of the peachalmond is 

 never converted into gum; in the almond itself such gum is found in rare cases 

 inside the shell. 



I/ (Hind gum in flic fruit-wall as a consequence of mechanical stress of the 



tissue. Gumming almonds. 



In many cases real wound gum is found in the fruits of the almond and the 

 peachalmond, not proceeding from the gum canals but from fractures in the paren- 

 chyma of the fruit-flesh. Its origin must undoubtedly be sought in the tension or 

 stress of the tissue, which causes the openinig of the fruit. An additional circum- 

 stance, however, is required, namely a loss of vital strength, by which the regenera- 

 tive power of the tissue that coats the fracture is annihilated. The thereform resul- 

 ting incapability of regeneration is associated with the ripening of the fruit in a 

 way not yet explained and should rather be attributed to superfluous than to poor 

 nutrition. Parasitism is wholly absent in the production of wound gum from the 

 parenchyma of the fruit. 



