DOTHIDEALES 



181 



(1934, 1935). Infection takes place in the spring; and, when the 

 host resumes growth the next spring, the invaded tissues rapidly 

 become enlarged, a velvety layer of conidiophores appearing 



Fig. 66. Dibotryon (Plowrightia) morbosum. A. Habit sketch of stroma 

 on branch of cherry. B. Portion of perithecial stroma in vertical section. 

 C. Conidiophores and conidia of the Hormodendrum stage. D. Ascus, un- 

 equally two-celled ascospores, and paraphyses. E. Conidia. F. Germmat- 



ing ascospores. 



over the surface of the swollen tissues. This conidial stage be- 

 longs to the form Genus Hormodendrum. After midsummer, 

 black stromata develop, covering the affected tissues, and by the 



