22 College of Forestry 



soluble in water, is readily soluble in alcobol. Continued 

 digestion with this reagent, however, finally dissolves the 

 gummy substance completely. ]\Iunch found that this reaction 

 took place in the substance with which he worked, especially 

 w^hen the mixture was hot; with a cold mixture, as a rule, a 

 greater time was required. 



Miinch (1910-), however, considers it an error of Frank, 

 which had not been disputed previously, that this reaction 

 (alcohol solubility after digestion with hydrochloric acid and 

 jDotassium chlorate) is a particular characteristic for wound 

 gum. He is of the opinion that the same reaction probably 

 also occurs with starch-containing cells which do not show 

 the slightest trace of browning or gum fomiation. As proof 

 of this Miinch treated thin sections of the inner, absolutely 

 white, living sapwood of Primus avium and Fagiis sylvatica 

 for ten minutes in the above-mentioned mixture. After this 

 treatment the rich starch contents changed into clear drops 

 which, upon the addition of alcohol, disappeared instantly 

 under the microscope. He found that the same behavior was 

 exhibited by the contents of the l)ark cells regardless of 

 whether they were living and colorless or dead, browned, and 

 filled wdth the brown substance. From the action of such 

 strong reagents, however, he failed to draw any conclusions 

 as to the nature of the substance. 



According to Miinch (1910^), the brown congealed product 

 of the cell contents arises not only in cells killed by dessica- 

 tion but likewise in cells killed by other causes. The recog- 

 nized browning caused by fungal attacks originates generally 

 from such substances only, in this case, they are less isolated 

 and in general occur mixed with the cell contents (remnants 

 of the protoplasm). Moreover, they are present here mostly 

 in slight quantity because the constructive product, the cell 

 contents material, has already been partially consumed by 

 the fungus. In order to prove this Miinch examined poplar 

 twigs which he infected while living with Siereum pur- 



