13 



Alternaria tenuis , variety X. Two other varieties, one rotting 

 the core of the apple, and one growing on the surface of the seed 

 and not rotting the fruit, while they are alike under the micro- 

 scope and the colonies look the same, do not behave in the same 

 way when inoculated on the fruit. The one causing this spot pro- 

 duces a rather rapid rot, the one from the core a slower growing 

 rot, and the one from the seed no rot at all. Several cultures 

 obtained from Mr. Elliott indistinguishable from these, produced 

 no rot on the apple. One, however, caused a spot not unlike 

 the one above described. It developed very slowly, and made 

 the skin dark, hard, and sunken. This was A. lascicul ata. of 

 the Aj tenuis group. 



Culture 8 



In culture the fungus produces a colony which grows very 

 rapidly. There is generally abundant white or grayish, cottony, 

 aerial mycelium (Plate 4, Fig. II) which covers a very large 

 number of spores produced from the internal mycelium. The under 

 side of the culture is dark, with numerous, more or less distinct, 

 concentric rings. The colony is indistinguishable from those of 

 a large number of Alternarias. 



The effect of different media upon the fungus is shown 

 in Table II. Cornmeal gave a darker colored colony than bean 

 (Plate 4, Figs. 2, 3) and a rather more abundant growth. The or- 

 ange juice in the cornmeal seemed to retard the growth for a time, 

 but not permanently. Under unfavorable conditions as in E. and F 

 the fungus spread over a greater area but was much lighter 



