CUCURBITARIA. 



209 



unicellular conidia, at first white, later grey. It is these pyenidia 

 which cause the fine perforations of the periderm of twigs. 



Yet another form of pyenidia, previously known as Diplodia 

 cytisi (Awd.), (N"o. 4). This, like the last, breaks through the 

 corky layers of the bark. It has a peridium composed of loose 

 pseudoparenchyma and, without the intervention of conidio- 

 phores, produces two- celled conidia of a dark greyish-brown 



Fig. 100. — Cucurbitaria laburni. Perithecium isolated. A, Ejaculating asc\is 

 ■with the inner membrane as yet unruptured, but emerging beyond the outer 

 ruptured coat. (After v. Tubeuf.) 



colour. This form, however, I failed to find in the course of 

 my investigation, although I looked through much material. 

 Tabulating these various forms of fructification we have : 



A. PyCNIDIA. 



1. White transparent, small, unicellular conidia on long conidiophores : 

 (a) Free on the stroma. 



(6) Enclosed in cavities in the stroma : 



(a) In cavities as yet not resembling pyenidia. 



(yS) In cavities with firm dark-coloured periphery. 

 (c) Enclosed in dark-coloured free pyenidia, with a peridium of coarse 

 pseudoparenchyma. 



2. Brown, unicellular, round conidia, in little brown pyenidia (Fig. 99, a). 







