352 H. MARSHALL WARD. 



that the disc is an asexual formation ; and such I interpret 

 it to be. The task of determining what takes place beneath 

 this disc has been the most difficult of all, not only on 

 account of the extreme minuteness of the structures to be 

 described, but also because their delicate nature, in contrast 

 with the brittleness of the rest of the fungus and the leaf,^ 

 renders it very difficult to obtain the necessary sections. 

 Partly from fresh specimens, and partly from preparations in 

 alcohol and glycerine, however, the following facts are to 

 hand. 



Vertical sections through the disc, &c., when the first 

 signs of its upheaval as a boss are apparent (figs. 14 and 15), 

 show that the space between it and the epidermis of the 

 leaf is becoming filled with closely packed, delicate hyaline 

 hyphse, forming a translucent meshwork, containing no air, 

 and very difficult to examine in the fresh state. By dissec- 

 tion and observations of the inner walls, it becomes evident 

 that these delicate filaments spring from branches developed 

 from the inside of the disc (figs. 20 — 22) ; these converge, 

 and form a mass of interwoven filaments in the cavity of the 

 boss, the increase of which forces up the disc in a dome-like 

 manner as described. It is in the substance of this dense 

 feltwork that the asci and spores subsequently arise. In 

 the meantime any of the larger hyphae which happen to be 

 encroached upon by the spreading disc above described, 

 become gradually broken up into short joints, which retain 

 their thin walls and pale colour (fig. o2). What becomes 

 of these '' toruloid '^ masses I cannot determine, and am of 

 opinion that the phenomenon is of an accidental nature, and 

 has no important bearing on what follows. 



At a stage somewhat later than that depicted in fig. 15, 

 one finds, from dissection of the boss or raised disc and its 

 contents, that a series of delicate, shortly jointed, branched, 

 and more or less coiled hyphse have arisen in the substance 

 of finer filamentous meshwork in the interior, and that 

 certain short branches, or lateral cells, of these become 

 densely filled with finely granular protoplasm, and rapidly 

 swell up into globular and pyriform bodies (figs. 21 and 18) : 

 these are the young asci. Each consists of a delicate cell- 

 wall enclosing the protoplasm. As the ascus increases in 

 size the contents become divided (figs. 23 and 24) into four 

 nucleus-like bodies, arranged in a tetrahedron in a mass of 

 more coarsely granular protoplasm. At a later stage, each 

 of the nucleus-like masses becomes divided again, and these 



The leaf becomes crowded with large crystals, apparently of calcium- 

 oxalate, slowly soluble without effervescence in hydrochloric acid. 



