Studies on Crown Gai.i. oi Plants 431 



Other workers contribukd " licrc and there, — cultures set, sec- 

 tions cut, llai;elhi stained, chemical analyses made." '•*' But for 

 two years Miss Haskins was the laboratory assistant, she pre- 

 paring in all several hundred plate cultures. To Smith she had 

 been recommended as a research worker in 1903 by her professor 

 of botany, W. F. Ganong, of Smith College. 



On February 21, 190 i, tlic Department had received from one 

 of the large commercial plant growers in New Jersey white and 

 yellow marguerites or Paris daisies {Chrysanthemum frutesceus) 

 infected with rrall-likc growths on the stems and leaves, and it 

 was stated that tlie galls appeared, without evident cause, on 

 plants grown in the open in summer and under glass in winter."" 

 Inability to secure the gall with regularity prompted Dr. Townsend 

 to abandon for a while the theory that the cause was bacteria 

 and to explore the effects of mechanical injuries on young and 

 old plants. In May 1906, however, after Dr. and Mrs. Smith had 

 sailed for Europe, one of the workers, presumably Dr. Townsend, 

 observed, while studying microtome sections stained with anil in 

 compounds having a strong affinity for bacteria, that although 

 " no distinct bacteria could be made out, nevertheless, that part 

 of the section lying deepest, i. e., bordering on the sound tissues, 

 took the stain much heavier than the rest of the gall as though 

 the living bacteria might be lodged most abundantly in this 

 portion. It was suggested, therefore, that for the next series of 

 plates deeper tissues should be used." New cultures were pre- 

 pared and in four from six groups of plates a yellow organism 

 developed; and in five from the six series " a few small, round, 

 white colonies appeared in each plate. . . . Slant agar and potato 

 cylinder cultures were made from both the yellow and white 

 colonies, also cultures in litmus milk." "' During June young 

 healthy daisy plants growing in the greenhouse were inoculated 

 with each of the four organisms at the top, middle, and base of 

 their stems. At least two sets of inoculations were made. On 

 June 18 knotty growths were visible and later developed into 

 " considerable size " in some of the pricked spots. 



Dr. Smith, before his departure, wrote in his journal: " Dcane 



'"E. F. Smith, Crown gall in plants, Phytopathology 1(1): 7, Feb. 1911. 

 ** E. F. Smith, The discovery of cancer in plants, Nat'l Geof^raphic M.i.^jzine 24 

 (1): 57, Jan. 1913; Crown-gall of plants: its cause and remedy, op. cit., 21. 

 ''"Crown-gall of plants: its cause and remedy, op. cit., 23-25. 



