FIELD STUDIES OF THE DISEASE. 43 



No. 422 was examined after 9 days and the inoculation hole was found to be 

 directly through the heart and to have caused a good soft, white rot. The effect on 

 the tissues was not limited to the softer ones in the interior, but was also evident on 

 the harder tissues of the strainers and leaf bases. 



No. 423 was examined after 11 days. The inoculation was found to pass immedi- 

 ately below the heart and to have caused an excellent soft, white rot, which affected 

 a considerable area of the tissues. There were also on this tree numbers of the leaf- 

 base spots. 



No. 248 was examined after 15 days, and the inoculation was found to have passed 

 15 centimeters above the heart and a little to one side. The excellent soft, white 

 rot was, however, spreading rapidly on all sides and above as high as 30 centimeters 

 from the inoculation. The extreme upper parts of the leaves were perfectly healthy. 

 In places where the inoculation passed through the strainers and leafstalks the rot 

 extended in areas anywhere from 1 to 30 centimeters in length; all of the tissues within 

 20 centimeters of the heart were badly rotted (PI. IX, fig. 2). 



No. 64 was examined after 16 days, and the inoculation was found to be rather 

 high and to one side of the center. A very little rot was present in the midrib of the 

 outer leaf. All the other tissues were not affected. 



No. 153 was examined after 16 days; very little sign of any rot was present. The 

 inoculation had caused a distortion of the inner tissues, but no other noteworthy 

 change. 



No. 189 was examined after 16 days and showed a splendid typical soft rot just 

 below the heart. The affected area extended for a distance of 10 centimeters above 

 and below the inoculation. 



No. 150 was examined after 16 days and showed an excellent inoculation which 

 had passed but 5 centimeters below the heart; the rot from it had passed into the 

 heart itself. Toward the outer side of the inoculation it passed through a young sword 

 which, as a result, had become rotted and blackened at the tip on the inner tissues. 



It thus appears that the successful infections were brought about 

 apparently by a variety of organisms. Following the examina- 

 tion of these inoculations, material therefrom was carefully selected 

 and sterilized on the outside surfaces so as to permit the transfer of 

 uncontaminated portions into bouUlon tubes, for the purpose of 

 pouring plates and thus isolating the organisms which were present 

 in the rotted tissues. Many plates were made and a variety of 

 organisms were isolated. In general two types seemed to be pre- 

 dominant; one type, most conspicuous, was the round white colony 

 with a raised surface, wet shining, and semiopaque. These colonies 

 in the course of two or three days attained, on a +15 nutrient agar, 

 a diameter of 4 to 8 millimeters, but seldom became much larger. 

 The other abundant type was of thin growth whose colonies spread 

 rapidly over the plate, i. e., where in one day's growth they might 

 have a diameter of 2 centimeters; in two days the growth might be 

 5 or 6 centimeters. 



Series of experiments were made in the Laboratory of Plant Pathol- 

 ogy at Washington, D. C, for the purpose of comparing the cultures 

 from the different trees. Plates of nutrient agar poured from the 

 diseased material showed in general the same type of colon}' as was 



228 



