HYPOCREALES 251 



antheridium and ascogonium are formed on the same hypha; only in 

 Claviceps there is no separation of a receptive organ, the trichogyne. 

 The unusual degeneration of the tip of the ascogonium, however, may be 

 connected with the fact that, like a trichogyne, it serves only for concep- 

 tion. In this case the trichogyne, although not morphologically present, 

 might be functionally so. Furthermore, the development of the fertilized 

 ascogonium of Claviceps is no longer independent, a fact which can only 

 be more definitely formulated by subsequent investigations. 



Our further knowledge of Claviceps is chiefly biological. In some of 

 the biological strains peculiar changes of host occur because the main 

 host is not in bloom when the sclerotia germinate (Stager, 1905, et seq.). 

 Thus the sclerotia on Brachy podium silvaticum normally germinate in 

 the spring. At this time, the panicles of this grass are still deeply 

 ensheathed so that infection is impossible. The fungus, however, can 

 support itself by infecting the earlier-blooming Milium effusum, which 

 grows with B. silvaticum, and produces the Sphacelia form on the 



Fig. 165. — Method of dissemination of two kinds of ergot sclerotia. 1. Sclerotia 

 between glumes of Brachy podium sylvaticum. 2. Sclerotia on Calamagrostis epigeios. 

 P, palea; Pi, palea inferior; Ps, Palea superior; G, awn functioning as organ of attachment; 

 S, sclerotia; H, Tuft of hairs. (After Stager, 1922.) 



former as an intermediate host, although the fungus rarely reaches the 

 development of the normal sclerotia. Meanwhile B. silvaticum has 

 bloomed, so that the fungus may complete its development there with 

 the sclerotial formation. Thus both hosts are necessary. We will 

 later meet relationships of this sort in Sclerotinia and in the Uredinales. 

 Interesting biological relationships have been found in connection 

 with the dissemination of the sclerotia. While in the form Claviceps 

 purpurea on rye, dissemination takes place mostly by man, Claviceps on 

 other grasses often uses the dissemination mechanism of the host or, by 

 its own adaptations, secures a passive motion in the surrounding medium. 

 In the first case, in contrast to the ergot of rye, the sclerotia remain firmly 

 attached between the glumes and then are spread by the host as if they 

 were naturally developed ovaries. Thus, on Brachypodium silvaticum 

 they utilize the awns for dissemination by animals (Fig. 165, 1); on 

 Calamagrostis epigeios they utilize wind dispersal mechanisms of the 

 host; in dry weather the umbellate crown of bristles at the base of the 

 glume spreads, and with a breath of air the sclerotia are wafted away (Fig. 



