98 C. D. Sherbakoff 



When the work was well under way and it became apparent that there 

 are indeed a considerable number of species of Fusarium, it came to 

 the writer's knowledge that the same thing was definitely proved, at 

 least for European conditions, by Appel and Wollenweber (1910) in 

 their Grundlagen (page 105), in which they state that most of the Fusaria 

 described by them were isolated from the potato, mainly from the tubers. 

 Since then this work has been continued with still greater confidence 

 in its underlying principles, but now mainly in order to verify the European 

 findings for the American conditions. 2 



All cultures of the Fusaria were obtained by isolations made from 

 diseased parts of the potato plant, mainly from tubers received from 

 pathologists in nearly every experiment station in the United States. 

 Of all the strains of the Fusarium-like organisms thus obtained, over 

 one hundred and twenty organisms at first seemed to differ in some way 

 or another. After a careful comparative study of all these strains, more 

 than half of the number proved to be identical with others. 



Some of the remaining organisms were identified with several Fusaria 

 described by Appel and Wollenweber (1910), by Jamieson and Wollen- 

 weber (1912), and by Wollenweber (1913, b and c). These are as follows: 



Fusarium affine Faut. et Lamb. 



F. coeruleum (Lib.) Sacc. 



F. dimerum Penz. 



F. discolor Ap. et Wr. 



F. Martii Ap. et Wr. 



F. metacroum Ap. et Wr. 



F. oxysporum Schlecht., as described by Wollenweber 



F. radicicola Wr. 



F. Solani (Mart. p. par.) Ap. et Wr. 



F. subulatum Ap. et Wr. 



F. trichothecioides Wr. 



Still other organisms were found to be very closely related either to 

 some of the species named above or to certain other species, at the 

 same time differing sufficiently from them to be separated on a con- 



2 The general discussion of the genus Fusarium was known to the writer before he began his work, when 

 in the summer of 1911 Dr. Jensen received the Grundlagen and now and then read parts of it to the writer. 

 Having no idea that Appel and Wollenweber were working mainly with the Fusaria of the potato, the writer 

 did not study their work thoroughly as early as he should have. 



