Gummosis in the fruit of the Almond and the 

 Peachalmond as a process of normal life. 



Proceedings of the Section of Sciences, Kon. Akademie van Wetenschappen, Amsterdam 

 Vol. XVI I, 1914, p. 810 821. -- Verscheen onder den titel Gummosis in de Amandel-en 

 de Perzikamandelvrucht als normaal ontwikkelingsverschijnsel in \ erslagen Kon. 

 Akademie van Wetenschappen, Wis-en Natuurk. Afd., Amsterdam, Deel XXIII, 1914, 



biz. 531543. 



It has hitherto been generally accepted that the formation of gum in the branches 

 of the Amygdalaceae always is a process of pathological nature. I have found 

 that this opinion is erroneous, and that gummosis occurs normally in the fruits of the 

 Almond (Amygdalus communis) and the Peachalmond (Amygdalus amygdalo-persica) 

 D u h a m e 1 D u m o n c e a u 1 ) . 



Contrary to what might be expected the phenomenon is the more obvious as 

 the trees are better fed and more vigorous. In specimens on sandy grounds it can only 

 be observed with the microscope. 



As gummosis is the effect of a wound stimulus, it is importance that this process 

 also takes place in the normal development of the healthy plant. The subject is 

 moreover of practical interest. All the chief facts relating to gum formation can 

 almost unchanged be applied to the production of gums in general, of gum resins, 

 and of resins, among which are substances of great medical and technical value. As 

 the study of the influence of parasitism has made it possible to produce gum, and 

 no doubt many of the other substances mentioned, in a more rational way than has 

 been done till now, a short review of the whole subject seems not superfluous. 



') In some Dutch nurseries the peachalmond is simply called Almondtree. The 

 difference is in fact very slight as it consists only in the drying up of the almond fruit 

 before the epicarp opens, and the position of the flowers in pairs, whereas the fruit of 

 the peachalmond remains fleshy even at the dehiscence, and its flowers are mostly single. 

 Between leaves, flowers and branches no constant differences are found. 



Grenier et Godron (Flore de France T. i, pag. 512, 1848) call the peachalmond 

 Amygdalus communis var. amygdalo-persica. At present the name Amygdalus persicoides 

 (Koch, Serin ge, Zabel) is also used, as in the Hortus of the University of Leiden. 

 The opinion that it is a hybrid is not sufficiently founded. When grown from seed the 

 tree seems constant (see Meijer's Conversationslexikon, Articks Mandel Bd. n, 

 p. 853 and Pfirsich Bd. 13, p. 782, 1896) and identic with the English almond, of 

 which Darwin reproduces a stone (Domestication, 2nd Ed., Vol. i, p. 858, 1875). The 

 fruit is fleshy and bursts open, the kernel is edible, not bitter. At Delft sowing ex- 

 periments have been going on a long time already, but under unfavourable circumstances. 

 The root cannot resist the winter temperature of the soil, hence, grafting on the 

 plumtree is required. 



