The fracture 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 normal living cells do not. These 

 necrobiotic cells and -the adjoining tissue produce gum. With the microscope not quite 

 dissolved cellwalls may be found in the gum, showing that the cells were about full- 

 grown when the process began. 



Fig. 3 (360). Gum canal with surrounding; gp gum; 

 xl xylum bundles, unchanged; ph non-dissolved cells 

 of the phloem bundles; cd threadshaped cells in 

 a gum canal, originating from the phloem bundles. 



In common almonds gum is sometimes found within the hard shell 1 ), and even- 

 tually part of the kernel itself is then also changed into real wound gum with still 

 recognisable remains of the cellwall. In such almonds 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 seed and is yet too labile to be demonstrated 

 by infection of bark wounds with gum. Experiments in this direction may perhaps 

 be effected with the peachalmond. 



Wound stimulus as factor of development. 



Formerly I thought that the presence of gum canals in the fruits was accidental 

 and should be explained by parasitism, although I could not find any parasites. 



') The small quantity of gum found, especially in hard almonds, at the surface 

 of the shell, proceeds from the gum canals of the fruit-flesh. The sugar layer which 

 covers the shell of the soft species is dextrose. 



