MYCOLOGIA 



Vol. XIII . JANUARY, 192 1 No. 1 



STUDIES ON PLANT CANCERS— II 



THE BEHAVIOR OF CROWN GALL ON THE 

 RUBBER PLANT (FICUS ELASTIC A) 1 



(With Plates i and 2) 

 Michael Levine 



Tourney (1900) in studying the effects of crown gall on the 

 host pointed out the destructiveness of this disease on deciduous 

 trees. He gave an adequate picture of the developmental stages 

 in the growth of the crown gall tissue on the almond. He con- 

 tends that the period of growth of the crown gall is definite and 

 usually extends over the growing season; after which time the 

 gall dies, falls out, leaving an open wound. In the following 

 spring a new crown gall is formed on the margin of the old 

 wound which in turn dies and increases the area of the lesion, 

 so that it weakens the tree and causes it to break off in a wind, 

 thus killing it. It appears from Tourney's study that death is 

 the result of a mechanical effect of the crown gall on the tissue 

 of the host in no way similar to the toxic effects that the can- 

 cerous growth has on the animal or human being. 



Hedgcock (1910 1 ) in his field studies of the effect of crown 

 gall on grape showed that the crown gall stunts the plant and that 

 when the galls occur on the stem under the ground they com- 

 monly decay, killing the adjacent tissue and often killing the vine 

 above the point of attack. Whether the decay is directly brought 



1 From the Cancer Research Laboratory, Montefiore Hospital, Dr. Isaac 

 Levin, Chief. The first paper was published in Bull. Torrey Club 46: 447-452. 

 pis. 17, 18. 1919. 



[Mycologia for November (12: 299-360) was issued December 27, 1920] 



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