148 Contribution to Knowledge of Silver-Leaf Disease 



seldom remain as permanent structures in the diseased Prunus leaves. 

 They are most probably very quickly dissolved in the cytoplasm, as 

 was found in the Nematode- galls by Nemec. Such an outward move- 

 ment of chromatin grains away from the nucleus is hardly a normal 

 process; it may be a symptom of pathological conditions in the cell, 

 just as is assumed for the Nematode- galls by Nemec, who says: "In den 



Figs. 18, 19. Binucleate cells from palisade tissue and upper epidermis respectively 

 Fig, 20. Part of palisade cell showing constricted nucleus. 



Riesenzellen der Heterodera-gaWen bei Washingtonia robusta treten zwar 

 in einem bestimmten Stadium regclmassig fast alle Chromatinkorner aus 

 dem Kern heraus, aber die Kerne degenerieren hierauf, und es scheint 

 daher, dass es sich urn einen pathologischen Vorgang handelt" (11, p. 483). 

 In a few cells I have found in the silvered leaves nuclear "frag- 

 mentation" or at least a tendency to it. In several palisade cells and 

 in a single epidermal cell two nuclei occur in close proximity to each 



