224 Investigations in Plant Pathology 



from yellows, proved that it could be spread in the same way by grafting 

 or budding, established that sometimes it did not occur in one side of a 

 tree when it was present in the other side although the following year the 

 entire tree became diseased, showed that when root grafts were made the 

 disease developed later on the top of the plant than when parts above 

 ground were budded with the diseased buds, found numerous gum-pockets 

 in the wood of the diseased roots (wood only of the season in which the 

 disease developed) and in the shriveling fruits, and showed that mere 

 contact of diseased tissues with wounds would not induce the disease but 

 that some fragment of the grafted wood or bark must heal on in order 

 to transmit the disease, although the tiniest bit was sufficient. There were 

 124 trees in my first budding experiment all but four of which contracted 

 the disease. The signs of disease appeared first around the inserted 

 diseased buds and a few months later the whole top became diseased. 

 These trees stood in two nursery rows and none of the several thousand 

 other nursery trees developed the disease. The cause of the disease was 

 not determined. 



Smith may not have found the cause. But he established several 

 fundamental conclusions necessary to a later more complete study 

 of this disease. In America his was the pioneering study and 

 helped to prepare the way for the career in science which was to 

 bring him eminence. June 11, 1891, he advised Galloway: 



Today I also discovered that certain cells of the phloem rays (in the 

 roots) are packed full of actively moving bodies 1 to ^/x in length. These 

 strikingly resemble bacteria and call to mind what we saw in the cells of 

 the carnation, but whether they are really germs remains to be seen. We 

 made cultures from the bark. 



We have made 25 cultures from various parts of diseased trees, but 

 shall have to wait some days for definite results. Some of the agar proved 

 to be cloudy and has behaved very badly. We have two or three sorts of 

 colonies and apparently one germ which liquifies agar. 



On June 13 Smith and Swingle notified Galloway that as soon 

 as their cultures would permit, they would go on, as instructed, to 

 Florida. They wished to complete, before leaving Georgia, some 

 inoculation experiments with bacteria they had found. They had 

 also some joint studies with the horticulturist of the " Georgia 

 Experiment Station." Swingle had become much interested in the 

 region's "vinifera" possibilities, and in certain fungicidal treat- 

 ments being tried against garden crop diseases, tomato, potato, egg 

 plant, sweet potato, in addition to other work. Early in the spring 

 Dr. J. C. Neal of Florida had sent the Department specimens of 

 the southern cabbage-worm {Plusia brassicae) affected with a 



