o H. MARSHALL WARD. 



at the opposite pole, or apex, is frequently a slight papilla, not ob- 

 viously pierced by any pore. Bornet, noting this fact, imagines that 

 the dehiscence takes place below, the whole upper part of the peri- 

 thecium becoming broken away by a circular rupture at the base. In 

 some forms, at least, the spores escape through an opening at the 

 apex : how far this is general I do not know (fig. 43), but facts exist 

 to render it probable that a minute and dilatable pore occurs in 

 others. 



Vertical sections of the mature perithecium show that within the 

 firm, deep-coloured, external wall is a lining of softer cells, with swollen 

 envelopes and of a more or less flattened form : this inner lining of 

 the perithecium extends two or three cell-series deep, and is slightly 

 yellow or pale-brown in colour (see figs. 33 and 34). In the cavity 

 thus enclosed are the groups of asci in various stages of development : 

 these delicate, clavate sacs contain spores, or have emptied them into 

 the semi-gelatinous, granular matrix around. 



With these preliminaries, I may pass on to consider and describe the 

 development of the perithecium, as followed step by step on a species 

 of Meliola which I have investigated with no slight success : 1 this 

 will be found to throw light on the morphology of these fungi from 

 the best of sources — development — and aid in a more critical estima- 

 tion of their proposed systematic position. After describing in detail 

 the origin, mode of development and fate of the fruit and spores, I 

 propose, therefore, to examine the relations of the Meliolas to Erysiphe 

 and other fungi. 



On examining portions of the epiphyllous mycelium bearing the 

 short pyriform, lateral branchlets so often referred to above, one fre- 

 quently discovers specimens presenting the appearances depicted at 

 figs. 9, 10, 11, &c. The simple pyriforrn body, after becoming more 

 swollen, has suffered division into two portions or cells by a septum, 

 usually vertical to the plane of the mycelium and leaf, and passing 

 diagonally across the cavity with a slight curve, so as' to abut on the 

 outer walls at right angles, or nearly so. The originally unicellular 

 protuberance becomes in this manner divided into two more or less 

 unequal cells, and it will be shown in the sequel that these two cells 

 have, from the first, each a different destiny in the formation of the 

 fruit. For this reason I have indicated in the drawings, by shading, 



1 I must take this opportunity of thanking Professor De Bary for kind suggestions with 

 respect to this work. 





