20 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



finally obtained. 1 These were supplemented by cultures of the 

 blackleg parasite isolated in Montana, Minnesota, and Maine. 

 For the sake of convenience all of the subcultures collected were 

 designated by a number. In order to facilitate matters, all 

 records of studies made on the strains selected were kept under 

 an assigned number. 



Below is given a brief note on the source and history of the 

 several cultures used more or less extensively throughout the 

 writer's comparative studies. The first 5 enumerated were from 

 isolations made in the Botany Department at the Montana Ex- 

 periment Station and were selected from isolations made from 

 potatoes affected with the blackleg disease obtained in some of 

 the more important potato-growing: sections of that state. 



No. 160.1. Isolated 8/14/15, from tuber affected with black rot. 

 Material from near Bozeman, Mont. Pathogenicity established. 

 Still virulent late in 1917. 



No. 170.3. Isolated 8/22/15, from tuber affected with black soft 

 rot. Material from near Lewistown, Mont. Pathogenicity established. 

 Still virulent late in 1917. 



No. 180.2. Isolated 7/24/16, from black, cortical lesions on stem. 

 Material from near Kalispell, Mont. Pathogenicity established. 

 Still virulent late in 1917. 



No. 183.2. Isolated 8/27/16, from black cortical lesions on stem. 

 Tubers on same vine affected with blackleg rot. Pathogenicity estab- 

 lished. Still virulent late in 1917. 



No. 187B.1. Isolated 9/2/16, from tuber with superficial black rot 

 lesions. Pathogenicity established. Still virulent late in 1917. 



No. 191. Kindness of W. J. Morse. His cl B. phiftophthorus from 

 Appel." Pathogenicity not established by the writer. Morse found 

 it non-pathogenic. 



No. 193. Kindness of W. J. Morse. His "III A," isolated by 

 him in Maine, Aug., 1908. Found by the writer to be pathogenic. 

 Still virulent late in 1917. Used by Morse in his studies ( '17). 



No. 194. Kindness of W. J. Morse. His "SE." Isolated by him 

 in Maine, Aug., 1908, from a "potato stem showing a very rapid soft 

 rot." Found bv the writer to be pathogenic. Still virulent in late 

 1917. Used by Morse (17). 



1 My thanks are especially due Dr. W. J. Morse and Dr. B. M. Duggar for 



very material assistance rendered in supplying certain of the cultures used in this 

 work. 



