A NEW APPLE TREE CANKER. 265 



tlic colouration, it intensifies it and stimulates its production. 

 < )n sonic tnedia. such as apple \\nofl chips, it seems to be neces- 

 sary. 



Light, moreover, seems to be essential for the development 

 f>f fruiting bodies, thus agreeing with Coons' (7) observations in 

 connection with Plcnodoniiis fuscomaculans. This fact accounts 

 for failure at first to obtain spores in culture : however, when 

 comparative cultures were made {see table), one series being 

 kept in the dark and the other in the light, the cause of the 

 >ierility of the fungus was found to lie in the absence of photic 

 stimulus. 



Fruiting bodies in the form of pycnidia, of Macrophoma 

 lype. were first observed iti cultures on Coons' solution which 



Text fig. 5. 



had been growing in the light. They were visible to the naked 

 eye as small bodies on the surface of the hyphal weft (Text 

 Fig. 5), the actual dimensions being 600 x 530/1. The spore- 

 (21 X 5/a) germinated readily in distilled water and in nutrient 

 solution. 



Besides the above pycnidia. bodies of a sclerotial or stromatic 

 nature were formed on various media in the light, potato 

 cylinders, rice and apple chips, being especially suitable ; forma- 

 tion of these bodies also takes place on Coons' solution and most 

 other media in the light. Drops of water exude from the sur- 

 face. (Plates XX V&, XX VI^, XXX&, also Text fig. 6.) 



