704 



"a universal [K'culiarity nl embryonic cells is concerned in this .i^umniy disso- 

 lution which, however, docs not extend so far as dissolution in normal life, 

 but only when caused by some further impetus." Kuhland investigated the 

 abnormal tissue groups, which may be observed in the production of the gum 

 canal and found cells enlarged to vesicles with two fully developed nuclei 

 but without the formation of any cell wall between them. The process is 

 explained by the adjacent Fig. 15O. 



Therefore, the cell iilaments, whicli extend into the gum centre, are 

 produced by the "repeated divisions of a cell which, not diseased, lies at the 

 base of the filament, while the daughter cells, thus produced, only increase in 

 size without division." The normal process of wall formation is arrested 

 in the embryonic cell and tlie carbo-hydrates, designed for the formation of 

 cross walls, are transformed into gum substances. The reason for the 

 change may be sought in the fact that, because of some injury, the embryonic 



Fig-. 156. Sections tiiroush gum-forming- tissue (fixed with cyirom-iicetiite 

 witli sal'runin-gentian-violet orange. (After liuhiiind.) 



stained 

 ./ a cell filament. />' a yoiiiiR Rruiu center: at a and f> cell.'; with two nuclei 



tissues are made accessiltle to the oxygen of the air; the carbo-hydrates, 

 really destined for cross-wall formation, will then pass over into the gum 

 which is richer in oxygen, (iriiss^ explains the oxidation by means of 

 oxygen carriers which are formed in the tissue during growth. W'iesner- 

 had earlier assumed a ferment which, like diastase, turns the guaiac emul- 

 sion blue and is destroyed by boiling. When treated with Orcin or hydro- 

 chloric acid, a red or violet color appears after a short boiling, and a blue 

 precipitate fornis. In the initial stage of gummosis, only the contents of the 

 I)arenchyma cells are found to discolor in this way, from which it may be 

 concluded that the ferment has its seat in the protoi)lasm. The ferment has 

 been pro\cd in tlie gums of seed and of stone fruit trees, in gum araliic and 

 other kinds of gum. Ruhland's experiments with the removal of oxygen, 



1 Oriiss, tjber Liosung u. Tiildiing d. aus Heinicclliiloso bestohi^nden Zc^llvviindc 

 und ihre Bezieliiuig zur Gummosis. Ril)l. bot Heft 39, Stuttgart 1896, Erwin Naegele. 



- Wiesner, tjljer ein Ferment, welche'^ in der F'flanzc die Umwandlung der 

 Cellulose in Gummi und Schleim bcwirkt. Bot. Zeit. 1885, No. 37. 



