f 



Halsted : Mycological Notes 



19 



na^a C. & P.). It was interesting to note that, in the present 

 stacre of the funsfus. a few mature perithecia were to be found at 

 or near the geographical center of the blotch, usually along side 

 of a vein and the hyphae extended radially to the margin. 



Fig. 2 



The fungus, judging from the size of the perithecia, must needs 

 have been upon the leaf long before any discoloration began to 

 take place and probably had spread to the full extent of the blotch 

 before its presence could have been detected by the autumn dis- 

 coloration. 



Much of interest centers in the action of the fungus upon the 



portion of the host that is under its immediate influence. Whether 

 it renders the affected protoplasm sluggish so that the chlorophyl 

 is not withdrawn, or the cells more active by supplying them with 

 the proper nourishment and the work of synthesis goes on as usual, 

 are conjectures simply and no explanation of the peculiar phenom- 

 enon in question. To look at the leaves it would seem to be a 

 case of symbiosis of the mutualistic sort. 



