258 



ASCOMYCETES. 



conidia germinate and give off long septate hyphae which, follow- 

 ing the course of the pollen-tube, reach the ovary, and soon 

 iill all four loculi with a white mycelium. The growth of this 

 mycelium proceeds from the central axis towards the walls, and 

 forms a hollow sphere open above and below. The diseased 

 berries cannot be distinguished till ripe ; then, whereas the 

 normal are red, the diseased are yellowish-brown to chestnut- 

 coloured, and soon shrink up, leaving only the outline of the 

 sclerotium. 



The dead or mummified berries fall prematurely, and lie over 

 winter on the earth. In April or May, the sclerotia give rise 



Fig. 136. — Sclerotinia oxycocci on Vaccinium Oxyeoccus. Toung shoot of Cran- 

 berry with mature conidial cushion and diseased upper leaves. A, Peziza-cup 

 developed from a sclerotial fruit ; numerous rliizoids proceed from the base of the 

 stalk. B, Ascospores in stages of germination. C, Conidia in germination, with 

 remains of disjunctors still attached. (After Woronin.) 



to several primordia or horn-like stalks, on the extremity of 

 which an apothecium is afterwards formed. Ehizoids are pro- 

 duced at the base of the stalk and attaching themselves to the 

 ground act as supports and organs of nutrition. The apothecia 

 contain both asci and paraphyses ; the latter are septate, dichoto- 

 mously branched filaments, with club-shaped ends, and coated 

 with a brown resinous substance. The asci have a canal at 

 one end through which are ejaculated eight spores of almost 

 equal size. These produce sporidia in water; in nutritive 

 solutions, however, they form a septate mycelium with conidia. 

 The ascospores bring about infection by means of one or two 

 germ-tubes which penetrate the outer membranes of young 



