Chap, in The Study of the Cryptogams 231 



of the nucleus of Peronospora during the formation of its 

 oospore. He investigated the features of nuclear division 

 in Cystopus, and in certain of the Ascomycetes and Hymeno- 

 mycetes in the years 1894-8. 



A great deal of interest centred in the Ascomycetes. 

 Tulasne investigated the structure and habit of the Ery- 

 sipheae in i860, and thenceforward carried out researches 

 throughout the whole group, in the course of which he un- 

 ravelled the curious life-history of Claviceps purpurea, the 

 Ergot. This was also studied by Kuhn in 1863. Janc- 

 zewski described the reproductive processes of Ascobolus 

 in 1871. Tulasne's earlier work on Penicillium was con- 

 firmed and extended in 1873 by Brefeld, who succeeded 

 in producing artificially its sexual fructifications, which 

 he found took the form of sclerotia. The sexual organs 

 were found to agree in all essentials with those of Eurotium 

 described by De Bary. Further investigations into the 

 sexuality of the higher Ascomycetes were carried out by 

 Harper in 1895. His researches on Sphaerotheca showed 

 the fungus to possess antheridia and oogonia, and to ex- 

 hibit various nuclear fusions of a sexual character. 



Stahl's researches on the structure of the Lichens, carried 

 out in 1877, furnished conclusive proof of the truth of 

 Schwendener's theory of their construction, which has 

 already been spoken of. Stahl produced artificially a 

 lichen by cultivating the spores of Endocarpon amongst 

 green cells or gonidia obtained from the same thallus, and 

 he found it bear both perithecia and spermogonia. He 

 discovered the carpogonia of Collema and some other 

 forms, which he found to be a coiled hyphal filament 

 projecting upwards from some little depth in the thallus. 

 The coils were low down in the latter, and the projecting 

 part was straight. Stahl called them the ascogonium and 

 the trichogyne respectively. He also claimed to have found 

 the spermogonia with their spermatia, and to have noticed 



