IOO 
Journal of Agricultural Research 
Vol. VIII, No. 3 
to believe that the disease was introduced into Maine from Canada. 
It should be noted, however, that Smith (33) reports having isolated 
B. phytophthorus , which he considers to be closely related to but not 
identical with B. solanisaprus , from potatoes grown in Maine. 
At the beginning of these comparative studies in 1908 an attempt was 
made to collect cultures of all the available organisms which had been 
described as causing a similar type of disease upon potato stems and 
tubers. 
So far as could be learned, B. airosepticus Van Hall was the earliest 
described species available. A culture so named was finally obtained 
from Kr&l’s Bacteriologisches Laboratorium, Prague, Austria. 
Difficulty was experienced in obtaining cultures of B. phytophthorus . 
The cultures were requested of Dr. E. F. Smith, of the United States 
Department of Agriculture, and of Dr. O. Appel, of the Biologische- 
Anstalt, Dahlem. Dr. Smith, while expressing a willingness to pass 
along the culture, stated that he preferred not to part with it till he 
had published on the subject. Two cultures bearing this name were 
received from Dr. Appel. These were apparently identical. Neither of 
them proved to be pathogenic, either to potato tubers or stems, on 
repeated inoculations. Apparently Dr. Appel had lost his original culture, 
from which, presumably, Dr. Smith’s strain was obtained, and writing 
under date of February 14, 1910, he stated that it had been necessary 
to make a fresh isolation of the organism before he could send it. The 
writer again wrote to Berlin in the summer of 1911, and a second culture 
was sent him. This reached the writer in February, 1912, by hand of 
Dr. W. A. Orton, of the United States Department of Agriculture, who 
kindly consented to bring it from Germany. Accompanying the culture 
was the following statement: 
B. phytophthorus is isolated from potato tubers by Dr. Schuster, 1911, at Dahlem^ 
Berlin, whose paper_on rot of potato tubers is going to be published. 
This culture was also found to be nonpathogenic to potato stems and 
tubers, and, as will be shown later, showed certain well-marked differences 
in its behavior on culture media when grown side by side with the culture 
received earlier from Dr. Appel under the same name. It should be 
remarked here that Dr. Appel recorded the fact that with him some 
cultures of B. phytophthorus showed a less virulence after growing for 
some time on artificial media. On the other hand, Dr. Smith (33, p. 749) 
states: "I have not observed any during a period of three years.” None 
of the other organisms studied by the writer have shown any loss of 
virulence on long-continued cultures, stock cultures being carried either 
in potato broth or beef-extract bouillon. 
My request to Dr. Harrison for a culture of 5 . solanisaprus was referred 
to Prof. S. F. Edwards, then of the Ontario Agricultural College, who 
furnished me with a virulent culture in March, 1909. 
