82 



largement of his field of vision. It is to be regretted that this publica- 

 tion has not received more attention, since one finds therein a 

 summary of his earlier work on the subject, viewed with reference to 

 his later opinions. New and fundamentally important, in the 1914 

 treatise, is Beijerinck's observation that in the over-ripe fruits of 

 the Peach-almond (Amygdalus amygdalo-persica Duhamel Dumon- 

 ceau), and to a lesser degree also in those of the Almond, gum- 

 formation in sieve tubes of the fruit wall occurs as a normal process, 

 whereby the possibility of infections or external wounds of that tissue 

 are excluded. Beijerinck supposes that the tender phloem, during 

 ripening and the subsequent drying up, is subjected to stresses which 

 lead to necrobiosis, and therefore to gummosis in this tissue, which 

 generally has little tendency thereto. 



This type of wound response should have to be regarded as one of 

 "the normal factors for the development of the fruit", thus being op- 

 posed to gummosis as the result of infections, of externally produced 

 wounds, or of poisons introduced. Thanks to the conception of "ne- 

 crobiosis", Beijerinck has been able to combine all these cases under 

 one common heading. 



