Studif-s on Crown Gai.i. of Plants 407 



bacterial potato disease, Sch\varx.beinigkeit (black Ic^), due to 

 this organism — a subject wliich was one of the main reasons why 

 the journey to Berlin had been made. Also guests at the dinner 

 were several of Aderhold"s assistants and Dr. Russe whose work 

 was then sugar beet diseases in Germany and tropical diseases in 

 the colonies and Dr. Maassen who had worked with Dr. Petri, 

 was now studying " diseases of bees and honeycomb, fowl brood, 

 black brood, etc.,"' and whose papers and acutcness of observation 

 Smith highly respected. Smith consulted these men in their labora- 

 tories several times. He gave Busse a serial slide of " stained 

 sections of a green- plum fruit attacked by Bacterium pruni . . . 

 one fairly illustrative of an early stage of the disease." A few- 

 days later Smith secured four " usable negatives and prints " 

 which admirably illustrated Dr. Appel's work on black leg of 

 potato. He had sent Dr. Aderhold a culture of Bacillus amy- 

 lovoYUS and was pleased to learn that not only was his culture 

 in the Anstalt's pathological museum but also that Aderhold 

 recently had secured with it " very interesting infections on green 

 pear fruits." 



Smith heard with interest their account of how much difficulty 

 they had experienced in isolating their Bacillus spongiosus from 

 diseased cherry stems. He was reminded of his years of trying 

 to isolate in pure culture Bacillus tracheiphilus, cause of cucumber 

 wilt. Furthermore, he was told that Bacillus spongiosus, isolated 

 from gummy cherry trees, " had no effect on the green pears, 

 neither would it blight green pear shoots in an earlier test. Dr. 

 Aderhold," wrote Smith, 



showed me a very instructive photograph of a youni^ pear tree with two 

 shoots, one inoculated with the Bacillus ainylovorous of my sending and 

 the other shoot with a young culture of his cherry organism; the former 

 shoot was killed in the course of a few days, the latter was not in the least 

 injured. There are some other interesting differences i. e., B. spojtgiosus 

 forms in gelatin plates (agar do. ?) very typical, and curious buried colonies, 

 " spongelike," Dr. Aderhold called them. It is a white organism making 

 a copious sirup on sugar agar. I saw plates under a low power of the micro- 

 scope. Tlie body of the colony produces curious involutions or twisted 

 folds, so that the main lines of growth or laminae of the colony are turned 

 in different directions as one lowers or raises the objective slightly. He 

 showed me cherry trees inoculated for some weeks and with no very 

 definite signs of disease beyond a little gum flow from the wound which 

 is not specific, but symptomatic of many things. I saw in the Museum 



