428 First European Journey 



valuable this has proved to us in our Station work and in the 

 class room, and also I hope that your courage is holding good 

 for the pushing of the work upon the subsequent parts." ''^ 



On April 26, 1907, Dr. Smith and Dr. C. O. Townsend of the 

 office of sugar beet investigations published in Science ^' their 

 very important announcement of "A Plant-Tumor of Bacterial 

 Origin." They said: 



The number of vegetable galls known positively, /. e., by exact experi- 

 ment, to be due to bacteria, is not very great. The discovery of a new one 

 of undoubted bacterial origin is, therefore, of considerable interest to plant 

 pathologists, and may be some interest to animal pathologists, especially 

 to those interested in determining the origin of cancerous growth. For two 

 years the writers have been studying a tumor or gall which occurs naturally 

 on the cultivated marguerite, or Paris daisy. It has been difficult to isolate 

 the organism and to demonstrate it unmistakably in stained sections. 

 Recently the bacteria (seen in small numbers in the unstained tissues on 

 the start) have been plated out successfully. With sub-cultures from poured 

 plate colonies, thus obtained, the galls have been reproduced abundantly 

 and repeatedly during the last few months, the inoculations having been 

 made by needle-pricks. . . . The organism attacks both roots and shoots. 

 It frequently induces abnormal growths on the wounded parts of young 

 cuttings. Its power to produce hyperplasia is not confined to the mar- 

 guerite. Well-developed small tumors have been produced in a few weeks 

 on the stems of tobacco, tomato and potato plants and on the roots of sugar 

 beets. More interesting economically is the fact that galls closely resem- 

 bling the young stages of crown-gall have been produced on the roots of 

 peach trees by needle-pricks, introducing this organism. In eighteen days 

 these growths have reached the size of small peas, the checks remaining 

 unaffected. It is too early, perhaps, to say positively that the cause of the 

 wide-spread and destructive crown-gall of the peach has been determined 

 by these inoculations, but it looks that way. Of course, the most that can 

 be affirmed absolutely at this writing is that we have found an organism 

 which when inoculated into the peach produces with great regularity galls 

 which in early stai^es of their growth cannot be distinguished from the 

 crown-gall. The matured daisy galls also look astonishingly like the peach 

 gall. Numerous experiments which ought to settle the matter definitely in 

 course of the next three months are now under way. 



During 1892-1893, when Smith first studied this disease, he had 

 not really begun his work in bacterial diseases of plants. Under 

 the microscope and with the use of culture media, he had examined 



*^ Burrill's letter was written February 6, 1907; Jones's, December 19, 1907; and 

 Hammond's, January 14, 1908. 



*=N.s., 25(643): 671-673, Apr. 26, 1907. 



