112 Transactions British Mycological Society. 



of the species of Fusarium which commonly occur on the potato, 

 and to settle the question as to whether it is a saprophyte or 

 a parasite. The species of Fusarium with which it has been 

 more closely compared in culture are F. Solani (Mart.) A. & W., 

 F. Martii A. & W., F. caeruleum (Lib.) Sacc, F. trichothecioides 

 Wr., F. discolor (A. & W.) var. snlphureiim (Schlecht.) and 

 F. arthrosporioides vSherb. 



Large numbers of cultures on numerous different kinds of 

 media have been studied and a variety of inoculation experi- 

 ments carried out, but it is only proposed to give a brief account 

 of some of the most important results here. 



General growth in pure culture. The stock pure culture which 

 served as the basis for all subsequent work was derived from 

 a single ascospore. These spores germinate readily, each cell 

 sending out a germ tube. A photograph of a germinated 

 ascospore is shown in Fig. i, Plate IV. 



Growth on all media used was luxuriant, the aerial portion 

 being usually copious and snow white. An eight-day old 

 individual growing on wort-gelatine is illustrated in Fig. 2, 

 Plate IV. No colour of any kind was ever developed, such as 

 is characteristic of several species of Fusarium. The older 

 growth, especially on media slanted in test tubes, is not fluffy 

 or cottony, as a rule, but may rather be described as somewhat 

 fibrous, that is to say, the hyphae combine laterally to form 

 more or less pointed strands, roughly comparable with fibrous 

 asbestos. None of the several species of Fusarium under study 

 at the same time showed this kind of growth. The consorting 

 hyphae are not merely mechanically adherent to one another 

 but actual anastomoses or "H-shaped" unions are frequent. 

 Cultures in Petri dishes show very distinct concentric zonation. 

 One such culture is shown in Fig. 4, Plate IV. Each zone 

 consists of a horizontal chiefly submerged vegetative growth of 

 mycelium and a corresponding vertical, aerial growth, the 

 latter consisting of conidiophores bearing conidia-globules and 

 being formed during the night. Each zone requires twenty-four 

 hours for its formation. Growth of this kind has not been 

 observed in any species of Fusarium. 



Conidiophores. These are usually long, erect, multicellular 

 and simple. Conidiophores with one or two lateral branches 

 are occasionally seen, but the mode and extent of branching 

 does not resemble that typical of Fusarium. They are some- 

 times submerged in the medium. Very frequently they are 

 aggregated together in the form of conical coremia, as described 

 and figured by Reinke and Berthold; and much of the aerial 

 growth of the fungus often consists of such coremia. The 

 second type of much branched conidiophores figured by these 



