JAMIESON AND WOLLENWEBER : FUSARIUM TRICHOTHECIOIDES 149 



a striking contrast to the smaller form (Fig. C). All the intermedi- 

 ate grades from the comma stage (like Trichothecium) to the 

 sporodochia stage are easily produced by a selection of media. 

 Beginning with the higher (sporodochia) stage we can reduce the 

 fungus to the inferior (comma) stage by means of a transfer of 

 mycelium; on the contrary, spores of the comma type once or 

 repeatedly transferred on grains or stems, will give normal sporo- 

 dochia with three to five-septate spores, sharply pointed at the 

 ends (Fig. B). 



The relationship to the discolor group may be determined only 

 by the higher form ; a confusion of the new fungus with F. discolor 

 and its variety " '' sulphureum" is impossible because F. discolor 

 differs by producing a purple mycelium, while that of ' ' sulphur- 

 eum" is brimstone-colored, and both differ from F. trichothecioides 

 by the absence of the comma stage. 



The occurrence of F. trichothecioides on other hosts is as yet 

 unknown. A comparison with earlier studies of other authors 

 shows that 5 different Fusaria cause similar tuber rots, 4 of which 

 are fully described: 8 F. solani (Mart.), F. coeruleum (Lib.), F. dis- 

 color var. sulphureum (Schlecht. s. sp.), F. trichothecioides Wol- 

 lenw. Probably Miss Longman 4 has dealt with a species differ- 

 ent from the four. She names it F. solani, but to judge from her 

 figures and her description, she had to do with a quite distinct 

 species. 



In order to prove the parasitic nature of Fusarium trichothe- 

 cioides, inoculation experiments have been carried on under con- 

 trolled conditions in our greenhouses during the past two seasons. 

 Potato plants, grown in sterilized soil, from selected and disin- 

 fected seed were used, and pure cultures of F. trichothecioides 

 inoculated into the stem just above the surface of the ground 

 (Dec. 1910). In twelve days a wilting of the foliage was noticed 

 accompanied by a yellowing of the leaves and a discoloration of 



3 Appel and Wollenweber: "Grundlagen einer Monographie der Gattung Fusa- 

 rium (Link)," Bd. VIII, Heft ], m., 10 Textfig.,2 schwarz.. 1 farbig. Doppeltafel. 

 Berlin: P. Parey u. ,). Springer. 1910. Preis, 10 M. 



4 Longman, Sibyl: "The Dry-Rot of Potatoes," T.innean Society's Journal, 

 Vol. XXXIX, Aug., 1909. 



