the Cause of Cherry Leaf Scorch Disease. 535 



In the subsequent stages of development of the perithecium 

 from the " coil " it is no longer possible to trace the ascogonia. 

 There is evidence to show that the ascogenous cells arise by 

 differentiation from ordinary cells. No fusion of nuclei has been 

 observed prior to that which occurs in the young ascus. 



The nuclear phenomena in the ascus are described in some 

 detail. Only a single process of reduction has been observed 

 which occurs at the time of the first nuclear division. It is not 

 possible yet to decide whether this division is heterotypic or 

 brachymeiotic though the analogies are with the former rather 

 than the latter. 



Thus only a single nuclear fusion and a single process 

 of reduction have been seen to occur in the life cycle of this 

 Ascomycete. 



