18 College of Forestry 



Miineli states that when tyloses occur in pathologic heart- 

 wood along Avith the decomposition products they have an 

 entirely different method of formation and cause than do 

 the decomposition products. It is his belief that they arise 

 earlier while the woody elements are still alive, as outgTowths 

 of the same. lie attributes their formation to the entrance 

 of air through a wound, that is, to wound stimulus.^ More- 

 over, these stimuli result in an increased transportation of 

 nourishment into the living tissues surrounding the dead 

 (infiltrated) portions of wood. If these enriched portions 

 of the wood are killed afterwards and infiltrated, the false 

 heart thus produced has (according to Munch) an appre- 

 ciably higher specific gravity than normal wood. The 

 occlusion of the vessels retards the ready access of external 

 air. Therefore the paucity of oxygen within the tissues of 

 living wood renders it less penetrable to fungal hypliae. 



ORIGIN OF THE DECOMPOSITION PRODUCTS 

 (KERNSTOFFE). 



The earlier authors did not agree as to whether the decom- 

 position products (Avound or protection gnm) arise as a 

 secretion product of living cells or as an oxidation product 

 of the dead cells. Frank's statement that the cells furnishing 

 the decompositioii products are living during the formation 

 of such substances never has been proved and it must suffice 

 to consider his theory as wholly hypothetical. Even Frank's 

 work does not appear to justify this statement and it appears 

 from it and still more from similar investigations by Will 

 (1899) that the formation of decomposition products cannot 

 be the result of a vital process. Frank (1884, p. 323) 

 described the microscopic details of Avound gum formation 



"According to Miincli (1910-) tyloses also occur at points where tlic 

 entrance of air is excluded and the stimulus afforded by fun<ious excre- 

 tions or decomposition products must be accepted as the reason for 

 their orijjin. 



