819 



The portion of the phloem bundles within the stone of the peachal- 

 mond is never converted into gum ; in the almond itself such gum 

 is found in rare cases inside tlie shell. 



Wound gain In the fniit-tnall as a consequence of mecltanlcal 

 stress of the tissue, (kiinnii/u/ 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 parenchyma of the fruit-flesh. Its origin 

 must undoubtedly be sought in the tension or stress of the tissue, 

 which causes the opening of the fruit. An additional circumstance, 

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

 regenerative power of the tissue that coats the fi'acture is annihilated. 

 The therefrom resulting incapability of regeneration is associated 

 with the ripening of the fruit in a way not yet explained and 

 should rather be attributed to superMuous than to poor nutrition. 

 Parasitism is wholly absent in the production of wound gum from 

 the parenchyma of the fruit. 



The fractui-e is mostly at the side where the two edges of the 

 carpels are grown together and the fruit later opens. Not seldom 

 in this case is wound gum seen to flow spontaneously from the 

 base of the fruit along the short peduncle. In other cases the wound 

 is at the side of the middle nerve of the carpel. Always the edges 

 of the fracture are coated with cells in a condition of necrobiose. 

 which is evident by their quickly colouring brown at the air, which 

 noi'mal living cells do not. These n«crobiotic cells and the adjoining 

 tissue produce gum. With the microscope not quite dissolved cell- 

 walls may be found in the gum, showing that the cells were about 

 full-grown when the process began. 



In common almonds gum is sometimes found within the hard 

 shell, ^) and eventually part of the kernel itself is then also changed 

 into real wound gum with still recognisable remains of the cell- 

 wall. In such almojids the phloem of the vascular bundles, which 

 run through the stone to the funiculus, is always changed into a 

 gum canal, so that the gum can reach the surface of the young 

 seed. 



If we suppose that gummosis originates by the action of a cytolysine. 

 it seems very well possible, that the lysine which has flowed inward 

 together with the ''canal gum", is able to attack the developing 



^) The small quaulily of gum found, especially in "liaid almonds", at the 

 surface of the shell, proceeds from tlie gum canals of the fruit flesh. The sugar 

 layer which covers the shell of the "soft" species is dextrose. 



