715 



describes these strips (Fig. 159) in the summer' wood. Up to the present 

 I have found them predominantly in the spring wood of our trees so that 

 a new annual ring begins at once with the abnormal wood, or after only a 

 few cell rows. I trace the production of these strips back to a transitory 

 weakening of the bark tension (see Frost Phenomena). This abnormal 

 wood parenchyma is shown in a complete stage of resinosis in Fig. 160. 

 Masses of resin, or rather amber, already produced, can push out the bark 

 away from the oldest part of the trunk. Conwentz found such bark ele- 

 ments in so good a state of preservation that he still could prove their 

 nuclei, (Fig. 161.) 



Nottberg found, in the liquefaction of the solid tracheid parenchyma, 

 that the tertiary membrane was retained longest ; this may be observed also 

 in the spreading of the gum centres of the cherry. 



pkmmamimi 



Fig 160. Horizontal section with abnormal parenchyma wood (P), which has begun 

 to turn to sugar. The abnormal tissue lies in the summer wood. J is the edge of 

 the annual ring. 210:1. (After Conwentz.) 



Nottberg distinguished good and evil wounds according to whether the 

 wound heals at once or affects the surrounding tissue. It should still be 

 noted that the trees, of which the wood normally has no resin canals at all 

 (the white fir), are found to abound in resin canals after injury, especially 

 in the edges of the callus. These investigations have been confirmed by 

 v. Faber\ who also emphasizes the fact that the pathological resin canals 

 are formed schizogenously. They anastomose in a tangential plane and 

 form a connected network, while their open ends extend into the wound. 

 Above these the resin canals are more abundant and longer than they are 

 below them. 



In opposition to the statements that the cause of resinosis may always 

 be sought in wounds, I must maintain, as in gummosis, that the processes 

 of liquefaction can also arise autogenously, without wound stimulus. I 

 have observed this in seedlings of pines from heavily manured nurseries. 



1 V. Faber, E. V. Experimentaluntersuchungen 

 flusses bei Abietiiipon. Dissertation. Hern 1901. 



die Entstehung d. Harz- 



