77 



Dept., University of Kentucky, Lexington, Ky.; Mr. James B. 

 McNair, 818 South Ardmore Avenue, Los Angeles, Calif.; 



Mr. George B. Rosebach, l >7 (lunch Street, Waltham, Mass. 



The resignations of Mrs. John T. Fetherston of New York 

 and Miss O.ardis B. Thayer of Philadelphia, were accepted 

 with regret. 



The first paper on the scientific program was on "The Tumor 

 producing Organism — Bacterium tumefaciens" by Dr. Michael 

 Levine of the Montefiore Hospital. The author's abstract fol- 

 lows : 



The bacterium which induces tumors or cancer growths on 

 plants has been known since 1911. The organism is a rod-shaped 

 cell which may be cultivated on a variety of media but appears 

 to grow best on a decoction or soup made of white beans. 



When this organism is introduced into a plant through 

 wounds produced experimentally by pricking it with a needle 

 or through wounds made accidentally by garden implements as 

 in the cultivation of the soil, the plant becomes infected. In a 

 short time, depending upon the plant, an overgrowth of tissue 

 in the injured region results, which has been called crown gall 

 or plant cancer. Cacti which have been studied recently show a 

 long latent period in tumor formation. The giant tree cactus 

 and the southern Opuntias produce galls experimentally in 

 about a year after inoculation. The galls grow for a relatively 

 long period, although the joints on which they are formed may 

 show partial necrosis. 



The organism which is responsible for these tumor growths 

 in plants undergoes characteristic changes which may be as- 

 sociated with changes in their ability to secure food. 



It has been mentioned above that Bacterium tumefaciens is 

 a rod-shaped organism measuring 1.5 u to 3 mX-5 u to .75 u. 

 A smear taken from a culture of this organism, grown on bean 

 broth agar and stained, shows these typical rods after two days. 

 Subsequent smears made at daily intervals for a period of three 

 to four months, show that the organisms diminish in size. At 

 two months or earlier ghost cells are observed with a number of 

 granular bodies. Examination of these cultures three or four 

 months later, even after the agar is dry and the colonies of 

 bacteria seem to have disappeared, shows these granular bodies. 

 When these bodies are transferred to fresh agar the rod-shaped 



