CORNELL UNIVERSITY EXPERIMENT STA.TION BULLETINS. 315 



stroma at the base of the pustules on the stem, but in the artificial cul- 

 tures do not seem to be especially concerned in the production of basidia 

 and spores, since but a few are developed in connection with them. 



Numerous basidia and spores are produced, however, all along the 

 threads and a mass of them at the point of inoculation. In a few days 

 more many fungus threads arise above the agar and produce a fluffy white 

 growth upon the surface, nearly obscuring the black points. 



No pigment was noticeable in these cultures. New cultures were then 

 started by transplanting portions of agar the size of a small pea with a 

 mat of mycelium and spores to fresh culture tubes. In the fresh agar the 

 growth took place in the same manner as in the first tubes, but upon the 

 surface of the transplanted portions a faint pink pigment appeared, similar 

 to that developed in some species of Gloeosporium and Colletorichum. 



Cell cultures were made in order to observe with the microscope the 

 different phases in germination of the spores and growth of the fungus. 

 Liquid agar containing a dilution of spores from one of the culture tubes 

 was poured upon a sterilized cover glass which was then inverted on the 

 ring of the cell. Figure 3, a, represents some of the spores in the cell 

 culture. They are oblong, usually pointed at one end, nearly cylindrical, 

 and either straight or slightly curved. The appearance of the contents of 

 the spores varies. Sometimes the protoplasm is nearly homogeneous with 

 one or more vacuoles, or it may be finely granular, with no vacuoles, or 



quite coarse granules may be 

 irregularly distributed in the 

 homogeneous protoplasm. The 

 latter condition is a very com- 

 mon one before germination, 

 ^and the behavior of these 

 j^^granules has suggested that 

 possibly they may be stored 

 products to be used during the 

 process of germination and 

 the early growth of the myce- 

 lium. It does not seem there 

 could be any need of such 

 stored products for spores in 

 artificial cultures where the 

 spore lies in a rich nutrient 

 media. But they might serve 

 the spores a good purpose in 

 natural conditions where the 

 sporejlies upon the surface of the plant and most often produce consider- 

 able growth of mycelium before the thread reaches nutritive tissues. 



In germination one or more germ tubes arise from the spore usually at 

 one side of the ends. Figure 3, b and c represents different stages in ger- 

 mination. The coarse granules are quite numerous, and in d some of 

 them have moved out into the forming mycelium. Figure 3, e represents 

 a further development of mycelium and also a further distribution of the 

 granules in the threads. 



Figure 4, a, b, and c are three camera lucida sketches of the growth 

 from a spore which was sown December 14, at 12:35 p. m. a represents 

 the growth which had taken place in exactly 24 hours, being sketched at 

 12:35 P. M., Dec. 15. 6 was sketched from the same object at 3:15 p. m. 



