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 tlie most part to enlargement of the cells 

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

 is completely lost (Figs. Q5, 66). The elements of the libro- 

 vascular bundles are enlarged ; the cells of the upper epidermis 

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

 thickened. All cldorophyll is destroyed in the pustules. 



Ex. polysporus (Sor.) causes swollen 

 spots on leuA^es of Ace7' tartaricum. 

 Ex. buUatus (Fuck.) causes similar 

 '^ spots on leaves of pear {Fyrus 

 ^^ communis) and quince {Cydonia 

 \_ jcifponica). 



[, Ex. Sadebeckii (Johan.) causes 



simple spots on leaves of Alnns 

 i/hifiiw-'^a. 



Many other species, named in our 

 list and in Sad check's papers, will be 

 found described in detail in one or 

 other of the papers already cited. 



K 





rm-.? 



Fici. Ii~ .— Exoaicm poli/sporus on 

 Ac(r tartaricum from Sweden. The 

 attacked leaf Hhows pule spots with 

 brown centres. The former result 

 frmii the To/>ltriita, and .ire covered 

 liy a white coating; of asci ; the brown 

 Mjiots are produced by other fungi 

 which grow on the spots already 

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



Jl Carpoasci. 

 {Ascomycetes loith SporocurjL/s.) 



The asci of the Carpoasci. are not 

 formed directly on the mycelium, but 

 from a special part of it, which 

 becomes more or less enclosed in 

 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 (b) the paraphyses and (c) the asci. 

 Amongst the Gyranoasci 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, 



