FUNGI. 



259 



from its attacks. The ovary thus becomes replaced by a soft white mycelial tissue 

 which retains nearly its original form ; the style being not unfrequently still borne on 

 its summit. The surface of the tissue of the Fungus is marked by a number of deep fur- 

 rows (Fig. 180, ^, and B, s) and forms a large number of conidia on basidia arranged 

 radially {C, p), imbedded in a mucilaginous substance which exudes between the pales. 

 In this condition the Fungus had been at one time considered a distinct genus, and 

 described under the name of Sphacelia. The conidia can germinate at once and imme- 

 diately again detach conidia (D, x), which, according to Kiihn, again produce a spha- 

 celia in other Grasses. The mycelium 

 of the sphacelia forms, when the pro- 

 duction of conidia has reached its 

 height, a thick felt of firmer hyphae 

 at the base of the ovary of the grass, 

 which is at first still surrounded by the 

 looser tissue of the sphacelia. This is 

 the commencement of the Sclerotium 

 or Ergot ; its surface soon assumes 

 a dark-violet colour, and grows to a 

 horn-shaped body, often as much as an 

 inch in length. In the meantime the 

 sphacelia ceases to grow, its tissue dies 

 and is ruptured beneath by the Scle- 

 rotium, and carried upwards on its 

 summit, where it is placed like a cap 

 (Fig. 180, ^ and B, j, sphacelia, c, scle- 

 rotium), and afterwards falls off. The 

 hard ripe sclerotium now remains till 

 the autumn, but is usually in a dormant 

 state till the next spring ; the for- 

 mation of the receptacle begins when 

 the sclerotium is lying on the damp 

 ground. The receptacles arise beneath 

 the skin, a nuiTiber of closely packed 

 branches being formed at definite points 

 from the medullary hypha* ; the bundle 

 breaks through the skin, and grows up 

 to a receptacle or stroma consisting of 

 a long stalk and a globular head. In 

 the latter a large number of flask- 

 shaped perithecia (Fig. 181, B and C, 

 cp) appear, which do not possess a 

 clearly-defined wall. Each perithecium is filled from the bottom by a number of asci, 

 in each of which several slender thread-shaped spores are produced. These spores swell 

 up in damp situations, and put out germinating filaments at several points. When they 

 reach the young flowers of rye, or of other nearly allied grasses, Ktihn states that the 

 sphacelia arises from them, and the cycle of development is thus closed. 



(4) The Diseomycetes \ This section includes, together with a number of incon- 

 spicuous Fungi, the striking forms of the Helvellea; and Morells, and the genus Peziza, 

 enormously rich in species. In the two first-named genera the hymenial layer over- 



FlG 180. — Claviceps purpurea; A a young sclerotium <r with the 

 old sphacelia J, • / the apex of the dead ovary of the grass; />' lon- 

 gitudinal section of the upper paj-t of A ; C transverse section 

 through the sphacelia, w« its mycelium, b the branches from whicli 

 the conidia are detached, 7v the wall of the ovary ; D germinating 

 conidia, forming secondary conidia jr. {A, B, C after Tulasne; D 

 after Kiihn). 



' De Bary, Ueber die Fruchtentvvickelung der Ascomyceten, • Leipzig 1863, p. 11. — De 

 Bary und Woronin, Beitr;;ge zur Morpliologie u. Physiologic der Pilze, and series, pp. i and 82, 

 Frankfort 1866.— Tulasne, Annales des Sci. Nat. 5th series, vol. VI. p. 247. 1866.— Janczewski, 

 Bot. Zeitg. 1871, no. 18. 



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