295 



2-3. A day or two later, early stages in the development of 



erect conidiophores. x 250. 



4. An erect branched conidiophore. x 250. 



5. Appressoria-like organs. Magnification slightly more 



than 250. 



6-7. Spores germinating in hanging drop. 



8. Spore germinating by budding. 



9. Spore germinating, showing four germ tubes. 



10. A group of spores from cooked-vegetable culture, 'showing 



slight irregularity of size and shape. 



freezing point were then placed at room temperature. Within a 

 few days that kept below freezing point developed in normal 

 manner, but in the tube kept at 24° C. the spores did not 

 germinate for some considerable time. Light does not seem to 

 be an important factor. The fungus grows more rapidly in 

 complete darkness than in diffuse light, but even in bright light 

 it makes good growth. 



Hanging-Drop Cultures. — Owing to the extreme readiness with 

 which the spores become detached, it was found very difficult to 

 observe the exact structure and development of the conidiophores, 

 except by hanging drop cultures. For this purpose a thin film 

 of potato agar was used. Germination takes place in one or other 

 of the following ways a few hours after sowing. Fresh spores 

 may be budded off or a mycelium may be produced, which grows 

 out indefinitely or terminates in a chain of spores. Two or more 

 lateral germ tubes are usually produced near one end, either base 

 or apex, of the spore, which is narrow and elliptical in shape. 

 The first few cells formed are often shorter and more swollen than 

 those of the normal hyphae. The latter are slender and uniform 

 in diameter, 2-4 /*, closely septate, at first hyaline but afterwards 

 pale brown. Towards the edge of the colony peculiar abortive 

 branches are to be noted which may, perhaps, function as 

 appressoria (see Fig. 5, p. 294). Anastomosis takes place, but 

 sparingly. The first formed conidiophores are usually decumbent 

 but the majority are erect (as seen in tube cultures) though never 

 attaining a height of more than 260 p.. The spores are produced 

 it the ends of short hyphae by means of acropetal budding. 

 These spores arise either terminallv or laterally with the result 

 that the branching of the conidiophores is quite irregular. 



Systematic Position of the Fixgus. 



From what has been said it is clear that the fungus isolated 

 is a Hyphomycete, belonging to the section Mucedineae, and that, 

 judging from the description given by Babenhorst (Krypt. Flora, 

 Band 1, Abt. 8, p. 352) it is not closely related to Spicaria 

 solani as had been suggested. In order to make certain of this 

 point Mr. Cotton kindly wrote to Dr. H. M. Quanjer, of the 

 Wageningen Phytopathological Institute for further details as 

 to this fungus. I am much indebted to Dr. Quanjer for a copy of 



