KUNKEL: SPORULATION IN MACROSPORIUM SOLANI 307 



were obtained in these cultures than when the atmosphere above the 

 fungus growth was allowed to remain near saturation. It was found, 

 however, that this method of treatment would not bring about very 

 abundant sporulation in the case of the early blight organism. A 

 number of other methods were tested, and the idea of wounding the 

 mycelium was finally hit upon. This seems to be the stimulus neces- 

 sary to bring about abundant sporulation in cultures of M. solani. 

 It will fruit profusely on any of the media above mentioned if the 

 mycelium is thoroughly wounded after the culture is two or three days 

 old and has made a good start. So long as the mycelium is undisturbed 

 it grows very vigorously through and over the surface of most culture 

 media. In these cultures very few conidiophores are produced and 

 very few spores are developed. Undisturbed cultures often fail to 



Fig. I. A wounded hypha bearing conidiophores of Macrosporium solani. 

 X650. 



Fig. 2. A wounded hypha of Macrosporium solani showing the production of 

 conidiophores near the point at which the hypha was cut. X 90o. 



bear a single spore. If, however, the radiating mycelial strands are 

 severed at the proper stage in the life of the culture, thousands of 

 conidiophores, each bearing a spore, will develop from the cells of these 

 hyphae. The wounding may be accomplished by scraping the surface 

 of the culture with a sterile scalpel or even with a strong platinum 

 needle. The more thoroughly it is done, the greater will be the 

 quantity of spores produced. 



Conidiophores arise abundantly near the point at which the 

 mycelium is broken. Sometimes each consecutive cell of the mycelium 

 for a considerable distance produces one or more conidiophores. Such 

 a series of fruiting cells is shown in Pig. i. At the distal end of some 



