KUNKEL: SPORULATION IN MACROSPORIUM SOLANI 309 



fields of Maine. They all responded in like manner, producing spores 

 in great numbers. The method has also been applied to other Macro- 

 sporiums that do not fruit readily in culture. M. tomato, Cooke, a 

 parasite of the tomato and M. daturae, Fautr., a parasite of the jimson 

 weed, Datura Stramonium L. respond in the same way to the wound- 

 stimulus. Although M. daturae fruits quite freely without this 

 stimulus, the number of spores produced in any culture can be greatly 

 increased by wounding. M. tomato fruits even more sparingly than 



Fig. 4. Fruiting culture of Macrosponum solani. This picture shows the 

 spores more highly magnified and indicates their abundance in a wounded string- 

 bean agar culture. X 250. 



M. solani in unwounded cultures. When thoroughly wounded it 

 bears spores in great numbers. 



The abundant sporulation of M. solani in culture makes more 

 easy the study of its fruiting stages. The successive steps in the 

 development of conidiophores and spores can easily be observed. 

 The mature conidiophores are always several-celled. They may 

 arise singly or in whorls, as is shown in Fig. 2. The typical conidio- 



