168 



ASCOMYCETES. 



the upper surface of the leaf (Fig. 64), and the upper epidermis 

 alone bears the asci. In the pustules, the leaf may be two to 

 four times as thick as healthy parts. The greatly increased 

 thickness is due for the most part to enlargement of the cells 

 of the mesophyll, while at the same time their normal arrangement 

 is completely lost (Figs. 65, 66). The elements of the fibro- 

 vascular bundles are enlarged ; the cells of the upper epidermis 

 are more numerous, contain a reddish sap, and their walls are 

 thickened. All chlorophyll is destroyed in the pustules. 



Ex. polysporus (Sor.) causes swollen 

 spots on leaves of Acer tartaricum. 



Ex. bullatus (Fuck.) causes similar 

 spots on leaves of pear {Pyrus 

 communis) and ^ quince (Cydmiia 

 japonica). 



Ex. Sadebeckii (Johan.) causes 

 simple spots on leaves of Alnus 

 ghitinosa. 



Many other species, named in our 

 list and in Sadebeck's papers, will be 

 found described in detail in one or 

 other of the papers already cited. 



B. Carpoasci. 



{Ascomycetes with Sporocarpa.) 

 Fig. 67. — Ej:oascus potysimmg on 



at"4uSlelr;LwTpS:f;,"tsw^^' The asci of the Carpoasci are not 



SrV/ wJ^dT/yv^ed foi-med directly on the mycelium, but 



«^;s'a«p™^fo°d by'it?'er''C5 ^''°'^ ^ ^pccial part of it, which 



which grow on the spots awy bccomcs morc or Icss euclosed in 



killed. 4 nat. size. (v. Tubeuf del.) 



another non-ascogenous portion. From 

 these two portions of the mycelium a sporocarp is formed, in 

 which we can distinguish three distinct constituents : (a) the 

 envelope containing (&) the paraphyses and (c) the asci. 

 Amongst the Gymnoasci the envelope, if present, is never 

 more than a loose hyphal tissue, but in the Carpoasci both 

 paraphyses and envelope are present, the latter with char- 

 acteristics distinctive of each species. The sporocarps of the 

 lower Carpoasci are completely closed structures containing 

 only one or a few asci ; those of the higher forms, however, 



