Last Work. Final Honors 581 



S. 3). Their experiments began in December, 1914," and, after 

 presenting what data concerning these he had been able to find, 

 Smith urged that the work be repeated for the purpose of veri- 

 fication. A tumor obtained with a one per cent solution of Sudan 

 III in olive oil by Dr. Nobumasa Umehara, professor of general 

 pathology and pathological anatomy in the medical high school in 

 Kyoto, Japan, was also described. Smith's interests embraced the 

 whole range of environmental and genetic influences in tumor 

 production. Each way to break " new ground " to solve the 

 problems of tumors was important. 



Since his years, belief in his general theory of chemically 

 induced plant galls has been consistently furthered. Many of 

 his conclusions, and those of other workers of his generation, 

 have undergone modification, revision, and refinement. But con- 

 sistently there has been an extension of many of the principles 

 which he first elaborated. There is an " extensive literature " ' 

 about auxins, which have been shown to be " particularly active " 

 in gall production. Mitchell, Burris, and Riker ^ have listed other 

 important more or less recent studies. They say: 



The use of lanolin as a carrier was a great improvement in experimental 

 procedure. With it chemicals could be released in continuing sublethal 

 concentrations over relatively long periods. Brown and Gardner (1936)* 

 grew crown-rjall cultures in media containing peptone with some trypto- 

 phan added. An ether extract of the culture was dried, incorporated into 

 lanolin and applied to bean plants. Excellent galls developed. No control 

 with the unfcrmented medium was reported. However, Kraus (1941) ^'^ 

 showed that 2 per cent tryptophan in lanolin was active. Also Brown and 

 Gardner used 2 per cent indole- 3-acetic acid in lanolin and secured 

 excellent galls. The concept has developed that a chemical cause of crown 

 gall has been found. 



In 1935 Miss Brown, still with the Department of Agriculture 

 and continuing her studies of Bacterium tumefaciens, thought of 

 producing a plant gall with indoleacetic acid and, in so doing, 

 made an important discovery. A growth substance was extracted 



' F. Skoog, Growth substances in higher plants, Atm. Rev. Biochem. 16: 529-564, 

 1947. 



* Inhibition of respiration in plant tissues by callus stimulating substances and 

 related chemicals, op. cit., 368-369. 



