CHAPTER V.—COMPARATIVE REVIEW.—ASCOMFCETES. 227 
formed closely woven thallus-structures (see page 43), which cause roundish red 
spots about I cm. in diameter in the still living green leaf; spermogonia and archicarps- 
make their appearance in the spots in the course of the summer. The Fungus does 
not go beyond the complete development and subsequent fertilisation of the archicarps 
during the summer, but falls to the ground in autumn with the leaf, and there the 
further development of the perithecium takes place, if the conditions are favourable, 
at the expense of the reserve of food in the thallus; the spores become ripe in the 
ensuing spring. The process can of course be to some extent hastened or retarded 
in plants under artificial cultivation by changes in the temperature and in the supply 
of moisture. 
The sclerotia of Claviceps purpurea and its nearest allies (see section VIII) mature 
during the summer and remain dormant all the winter; in the next spring each 


FIG. 108. Clauiceps purpurea, Tul. 4 jum which has given rise to seven FIG. 109. Claviceps purpurea, 
stromata. B upper portion of a stroma in median longitudinal section; ¢ perithecia. Tul Ascospores germinating 48 
C highly magnified perithecium divided through the middle with the surrounding hours after being scattered on 
parts; of orifice, sk cortical tissue, %y inner tissue of the stroma. D ascus isolated; sp water. Magn. 375 times. 
ascospores issuing. After Tulasne from Sachs’ Lehrbuch. A natural size. 2 slightly, 
C and D highly magnified. 
sclerotium, ifit happens to lie on moist ground, usually produces several spherical stalked 
stromata (Fig. 108 A), the upper spherical portion of which is thickly covered with 
perithecia sunk half-way beneath the surface (B, C). The ejected cylindrical filiform 
ascospores (2) swell in different parts under the influence of moisture, and put out 
germ-tubes at several points (Fig. 109). If the ascospores of Claviceps have found 
their way into young flowers of the Gramineae (Secale in artificial cultivations) under 
conditions favourable to germination, their development begins in the pistil, according to 
Kühn’s observations, and doubtless after the germ-tubes have penetrated into the pistil, 
though this has never been directly observed. The young pistil concealed between 
the paleae is first of all traversed in every direction and enveloped by a luxuriant 
growth of the hyphae of the Fungus, as has been already described : a white hymenium, 
Léveillé’s Sphacelia, then forms on the whole of the furrowed surface, and from cylindrical 
sterigmata on it gonidia are abscised (Figs. 110, 111 a). During the formation: of 
Q2 
