784 



which have extended farther each year, has been formed over the surface 

 of the wound and has finally closed it. The overgrowth in this case has 

 taken place principally from above, since most of the plastic material has 

 come from that direction. In a slender, longitudinal wound the overgrowth 

 takes place principally from the sides. 



The process of overgrowth, which sets in in the branches of trees, also 

 causes the closing of wounds on cut or chopped surfaces of stumps left 

 when trees are felled. The process extends only comparatively slowly, 

 since the cambial ring producing the overgrowth edges has to cover a very 

 large wound surface. The result is that, long before the overgrowth edge 

 has reached the central part of the cut surface, this has decayed and the 

 center of the branch in consequence has become hollow. The overgrowth 

 masses now sink down into the cavity in very different forms and, at times, 

 in twisted cords covering projecting si)lintcrs or stones. Thus they can 

 attain a considerable size\ 



The question is now pertinent, whence comes the material necessary for 

 such an extensive new formation. The opinion usually expressed is that 

 the reserve substances, formed before the felling of the tree and present in 

 the stump, can be the only source of all the new structures. In other cases, 

 root union, which occurs not infrequently, is used to explain this, for it is 

 assumed that the stump is nourished by the uniting of its root branches with 

 the stronger roots of adjacent trees, which still retain their crowns. 



Certainly, cases of this kind are not rare in larger tracts of trees- and 

 such a nourishing trunk can actually give considerable assistance to the 

 stump. Nevertheless, there also exist instances in which absolutely isolated 

 trees have formed such large overgrowth masses on the stump that the 

 supposition of a production of such massive new structures from the reserve 

 substances alone does not seem sufficient explanation. 



In my opinion, however, there exists universally in such cases an acces- 

 sory apparatus, which is capable of conveying newly assimilated material. 

 If the young overgrowth edges are investigated more or less chlorophyll 

 will be found in their bark, according to the amount of light the trees receive, 

 and it is by no means clear, why this chlorophyll apparatus should not 

 assimilate just as well as the green bark of the trunk. The fact that 

 branches are found growing out of older overgrowth edges shows how 

 abundant is the life prevailing in them^. 



The formation of branches from the cambial ring of tree stumps is a 

 very common occurrence, which comes to view on all sides with felled 

 poplars and arises from the production of adventitious buds in the paren- 

 chymatous overgrowth tissues. 



1 Good illustrations of such cases in Goppert, Nachtrage zur der Schrift tiber 

 Inschriften und Zeichen in lebenden Baumen. Breslau, Morgenstern 1870. 



2 Goppert, Beobachtungen iiber das sogen. tjberwallen der Tannenstocke. Bonn, 

 Henry & Cohen, 1842. 



3 V. Thielau, in Lampersdorff near Frankenstein in his advertisements of the 

 Goppert Treatise (tJber die Folgen aussersr Verletzungen der Bilume, etc.) in May, 

 1874. 



