Last W'oi^k. I-inai, Honors 595 



buds. They su ingest," he wrote in his diary May 22, " the tume- 

 factions I got on Bryophylkim by moving from cool to warm 

 house." Since 1908 he and Miss Brown had recognized that the 

 apple strain of the crown gall organism possessed a tendency 

 under definite conditions to produce roots in conjunction with 

 tumors. In liis textbook of 1920 '^ he had said: 



In 1916 the writer discovered crown galls bearing leafy shoots and 

 sivbsequcntly produced many by needle-puncture inoculation on stems and 

 leaves of tobacco, Pelargonium and other plants. Earlier than this by some 

 years, Miss Brown and 'myself had demonstrated that crown galls may bear 

 roots (hairy root of apple, etc.) but I did not then perceive the full 

 meaning and trend of this discovery, viz., that because the type of a crown 

 gall depends on the kind of tissues inoculated it should be just as easy to 

 produce tumors bearing leafy shoots or flower buds as roots. This had to 

 be stumbled upon to be seen, like many another perfectly obvious thing. 

 Its discovery, however, it seems to me, adds very considerably to our knowl- 

 edge of the nature of crown gall and throws a flood of light also on the 

 origin of animal teratomas. 



Crown galls occur very often on what gardeners call the 

 " crown " oi the plant. They may develop on any part of the 

 root or shoot, and are " very common above ground on the 

 branches of the daisy, grape, quince, apple, rose, willow and 

 poplar. They are also common on the roots of a variety of plants 

 but must not be confused," Smith pointed out,"' '" with root galls 

 due to nematodes." In 1908 he expressed " little doubt " " that 

 hairy root of the apple is of bacterial origin and caused by a 

 " similar if not identical organism " as in the case of crown galls. 

 The crown gall and hairy root bacteria have since been differen- 

 tiated." Infectious hairy root of apple is now belived to be caused 

 by Phytomonas [Bacterium'] rbizogenes, an organism distinguish- 

 able from Bacterium tumejaciens. 



In 1925, in the Journal of Heredity,"" Dr. Smith published 



*' Intro, to bcjct. dis. of plants, op. cit., 419, 421. 



^ndem. All. 



*^ The etiology of pl.tnt tumors, op. cit., chap. VIII. See also, N. A. Brown, The 

 tendency of the crown-gall organism to produce roots in conjunction with tumors. 

 Jour. Agric. Res. 39(10): 747 ff. (G. G. Hedgcock accredited with establishing in 

 1905 the pathological effect of crown gall on orchard trees. Crown gall and infec- 

 tious hairy root of apple considered also as the same disease). 



*' A. T. Riker, Studies on infectious hairy root of nursery apple trees. Jour. Agric. 

 Res. 41(7): 507 ff., Oct. 1, 1930. 



*' 16(8): opposite p. 273, Aug. 1925. 



