Behavior of Crown Gall on Rubber Tree. 



157 



83 (1543) 



The behavior of crown gall on the rubber tree (Ficus elastica). 



By Michael Levine (by invitation). 



[From the Montefiore Hospital, Cancer Research Laboratory, 



New York City.] 



Smith (1911-12) in his extensive studies on crown gall and 

 its resemblance to animal cancer shows that the physiological 

 effects of these tumors vary from species to species and also within 

 the species and are generally less pronounced and speedy than one 

 might expect. He holds that it is difficult to show conclusively 

 that the substances produced in the tumor by the parasite are 

 absorbed and act as slow poisons. This is expecially difficult in 

 view of the fact that the galls are often soaked by rains and become 

 infected with other parasitic and saprophytic organisms. 



Levin and Levine (191 8) in a preliminary report on the malig- 

 nancy of the crown gall and its analogy to human cancer pointed 

 out that a number of the phenomena in both diseases are analogous. 

 They contend that the neoplasms in plants produced by Bacterium 

 tumefaciens are sometimes benign, though some are true malignant 

 growths. The latter generally dwarf the plant so affected and 

 cause the necrosis of the tissue above and below the gall. 



These studies and those of other workers were carried out on 

 annuals, biennials or deciduous trees in which the period of growth 

 of the host as well as the crown gall is normally interrupted. 

 The difficulty in determining the effects of crown gall, is made 

 greater by the intervention of natural death, caused by changes 

 in temperature and its concommitant factors, and second, by the 

 occurrence of infections caused by fungi and even insect grubs, 

 the eggs of which are deposited in the soft tissue of the young 

 crown gall. 



The purpose of this report is to bring forward further evidence 

 on the malignancy of the crown gall experimentally induced 

 on mature evergreen perennials such as the common rubber 

 tree, Ficus elastica. In such plants where the growth is rather 

 active all the year round, when kept under uniform, green house 



