18:3 

 brooms" . 



Abnormal Wood . 



The numerous woody-galls produced by many 'funpi fG-vmnos- 

 porangium. Peridermium. Dasysc^ha, llectJia? Agalafspo^IT 

 ton-^\ ?Q ;•' parasitic phanerogams (Loranthaceae) ejid insects 

 (203) (Schizoneura, Lachnus , etc.) have been subjected ±n part to 



closer anatomical investigation. So far as known, all woody- 

 galls are characterized by the abnormally abundant parenchyma 

 development, recognizable in the structure of wound-wood. 



Increase of the parenchymatic elements can be produced 

 here and there by segmentation of the young derivatives of 

 the cambium, which thus furnish groups of parenchjrmatic cells, 

 instead of growing out into prosenchymatic xylem elements.- or 

 by the corss-division of the cells of the cambium itself and 

 Jh§ production, after further division, of parenchymatic pro- 

 ducts. Either the cambial cells are only changed in places 

 as described, so that the cambial rays are broadened and their 

 number seems increased,- or the cells divide over the entire 

 araa of infection, so that extensive, continuous masses of 

 parenchymatic wood are produced. No difference in principle 

 may be proved between Myoocecidiae f fungus- galls) and Zooce- 

 cidiae (animal-galls) . 



We will begin v;ith an example from the list of Myooce- 

 cidiae. 



As is well known, ■ the gymnasporangia produce spindle- 

 like or ball-like woody-galls on different species of Juniper 

 (J. communis Sabina. etc. ) lornia"^ has studied their 

 s tructure thoroughly. According to his statements, the dif- 

 ference betv/een spring and autumn wood is not expressed nor- 

 mally in diseased wood, the annual boundaries are scarcely 

 recognizable. Besides this, the parenchymatic elements in 

 the wood require themselves a noticeably broad space. Instead 

 of being only 2 to 10 cells deep, the cambial rays in the 

 parts of branches infected by Gymno sporangium cla^ariae forme 

 are often 10 to 20, even 60 cell layers depp,- and as many as 

 3 cells broad. Still broader cambial rays are found in the 

 tangential longitudinal section through the woody-gall of 

 G. juniper inum shown in figure 77, Further variations from 

 aA aaSMAl esOHMSiQH are found in the hypertrophied petrenchyroa 

 cells, which assume a "shapeless form" and disturb the radial 

 arrangement of the tracheids (V/orni©,, loc. cit. p, 146) and 

 further^ in the occurrence of distended ^jsEenchyma-cell centers 

 which Wornia in one case found broadened to one sixth of the 

 (204) whole size of the branch. They extend partly in the direction 

 of the cambial rays, partly in the vertical direction of the 

 parenchyma of the cord. In cross-section it is clear that 

 they are separated only by slender^^ tracheid-groups, often 

 consisting of one row.iof cells. V/ornle's discoveries do not 

 throv; sufficient light on the development of these abnormal 

 tissues. Yet I would like to assume that the first named, ab- 

 normally broad cambial rays are brought about by segmentation 

 of the cambial cells, the last named ^pftrenchyma centers by 



1. Anat. Untersuch. d. durch Gyranosporangium-Arten hervor- 

 geruf enen Missbildungen. Forstl.-Uaturv/iss. Zeitschr. , 1894, 

 Bd. II, pi 68, 



