192 CROWN-GALL OF PLANTS. 



and Washington State. In general it is easily distinguished from the 

 attacks of nematodes (PI. IV, fig. 1). It is less easily distinguished 

 from what we have called tuberculosis of the beet. The latter occurs 

 in Kansas and Colorado. It appears to be most prevalent in Colorado 

 where at least one field was badly injured. According to one of our 

 correspondents it is on the increase. Should this disease become 

 widespread the yield of sugar would be greatl}^ reduced. 



Crown-gall seems to be rather infrequent in Germany, judging 

 from Dr. Reinelt's paper in Blatter fiir Zuckerriibenbau (Berlin, 31 

 Marz, 1909), since with the assistance of various sugar-beet men he 

 obtained only 47 specimens for his studies. 



According to Dr. K0lpn Ravn, of Copenhagen (oral communica- 

 tion), the gall occurs on sugar beets in Denmark, but does not injure 

 the crop, only about one beet in a million showing it. 



Of 3,247 beets dug in November, 1910, in Virginia (Arlington 

 Experimental Farm), 5 bore tumors. 



The galls on the beet often grow to large size, e. g., Reinelt men- 

 tions some as large as a child's head or larger (weight 1.5 kilos), 

 others which caused thickenings of the whole or a great part of the 

 root, and still others which were small as peas, but set close together 

 over the whole surface of the root. 



This gall we believe to be due to the crown-gall organism. Three 

 times prior to 1910 typical looking colonies on agar poured plates 

 were obtained from the interior of beet galls from Cahfornia and once 

 from Virginia. The Virginia colonies were not transferred to sub- 

 cultures, and the two or three colonies selected from the California 

 plates proved nonpathogenic to sugar beets; no additional oppor- 

 tunity for making poured ,plates occurred until November, 1910. 

 (See pp. 81-85.) 



Reinelt failed to isolate bacteria from the inner tissues and comes 

 to the conclusion that bacteria are not present. He used various 

 sorts of gelatin media. His technique of surface sterilization appears 

 to have been proper and the source of his failure appears to have 

 been (1) that he selected improper material (too old), (2) that he 

 did not wait long enough for the bacteria to appear on his plates, or 

 (3) that he diluted his infectious material too much. The period 

 the plates were under observation is not stated. He should have held 

 his plates for at least ten or fifteen days ; he should also have mashed 

 up the fragment of beet and inoculated copiously from the first tube, 

 whereas he did not crush his material but only allowed the small 

 cube to remain in the bouillon for a short time and then made his 

 inoculations from a third transfer (third tube). Judging from our 

 own experiments, on daisy galls, the third tube of bouillon prepared 

 in the manner he describes would ordinarily contain very few living 



213 



