328 



after isolation, — "the breast high growth, measuring 1.2 sq. cm. in cross- 

 section, in a few years increased in cross-section growth to 13.7 cm. ann- 

 ually \" The cork was split thereby in numerous places and resulted in a 

 rupturing, indeed, in places it lifted the bark body from the wood-cyUnder. 

 Hartig found similar conditions in oaks and explained this by a greater 

 soil activity, resulting from the isolation and increased action of light'-. 



I^henomena of tliis kind may be found also in other trees, especially in 

 ])arks and gardens. 



Shedding of the Bark. 



Hartig describes a case in which the splitting of the bark is due to an 



increase in the normal 

 growth. I observed a 

 splitting and shedding 

 of the bark from an ab- 

 normal cell - elongation 

 in the bark parenchyma. 

 In 1904, I found in an 

 a\cnue of elms a num- 

 ber of trees standing 

 side by side at the bases 

 of which a great many 

 pieces were perhaps as 

 long as one's hand. 

 Upon closer investiga- 

 tion, loosely hanging 

 strips of bark 25 to 50 

 cm. long were found on 

 llie lower end of the 

 trunk, which could easily 

 be removed. The trunk, 

 thus exposed, was cov- 

 ered with greenish tis- 

 sue in spots which 

 proved to be new for- 

 mations of bark. The 

 loosened pieces of bark 

 (Fig. 45), exhibited on 

 t!ie inner side flat, light brown cushions irregularly distributed and differing 

 in size and thickness. Having a spongy consistency, they easily gave way 

 to the pressure of a finger-nail. Here and there, between them could be 

 seen crater-like, harder, small protuberences. The upper surface of the 

 cushion was smooth ; it was rough and sometimes woolly in places because 

 of prominent, hair-like processes. The part of the Itark remaining on the 



.hion-like, 



of a fallen piece 

 protruding- tissue 



of elm 

 islands. 



1 Lehrbuch der Prtanzenkrankh, 1900, p. 261. 

 3 Unters. Vol. I, 1880, p. 45. 



