DISCOVERY OF THE BACTERIA. 21 



from Georgia. He did not then have bacteria in mind, but rather 

 l)lasmodia and iungi, cspccialh^ the latter, an effort being made to 

 connect the growths with certain roundish brown chlamj^dospores 

 found very abundantly in some of the galls. Nothing was published 

 on the subject, because the conclusion was finally reached that 

 neither plasmodia nor fungi were the cause of the disease. 



Thereafter none of us (the writers) did anything with the subject 

 of crown-gall for a period of 10 years — i. e., until 1904. 



In the interim other workers in the Bureau of Plant Industry 

 took up the subject — i. e., Waite,0'Gara, von Schrenk, and Hedgcock, 

 but without discovering the cause. It may also be added that in 

 beginning work on the daisy gall the writers had no idea that it would 

 reopen the whole subject and lead in all sorts of directions. 



STUDIES DETAILED IN THIS BULLETIN. 



DISCOVERY OF THE BACTERIA, FIRST ISOLATIONS, AND 



INOCULATIONS. 



In Februar}^, 1904, the Bureau of Plant Industry received a 

 number of marguerites or Paris daisy plants (Chrysanthemum frutes- 

 cens), both white and yellow varieties, all of which were affected 

 with gall-like growths on various parts of the stems and leaves. 

 These plants were sent in by one of the large commercial daisy grow- 

 ers in New Jersey, and were accompanied with the statement that 

 both old and young plants were attacked, but that the older ones 

 were more seriously affected than the younger ones. The further 

 staten:ient was made that the disease appeared on the plants in the 

 open in summer and in the greenhouse in winter, and that the galls 

 appeared on stems and leaves without any apparent cause. The 

 galls received varied in size from one centimeter to several centi- 

 meters in diameter. The smaller and younger galls were green 

 in color, nearly smooth in appearance, and soft and spongy to the 

 touch. As the galls became older they increased in size and darkened 

 in color externally until they were distinctly brown, the surfaces 

 were rough (corky), sometimes convoluted, and they were firm 

 and hard. All gradations were noticeable, so that regardless of 

 the unlike appearance of the different galls, it was evident that they 

 were all of the same origin. New galls appeared from time to time 

 after setting out the plants in our hothouse. 



The various conditions under which the galls formed excluded the 

 possibility of their being due to insect injuries. A careful examina- 

 tion of the galls for fungi resulted in none being found in the interior 

 of the tissues, and only one was found on the surface — a Macro- 

 sporium — which occurred on a portion of the knots and which had 



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