ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 685 



with the Hyphomycete Costantinella cristata. He thinks that it might 

 be included in the genus Botrytis. The conidial form is produced 

 where there is a high condition of moisture. Conidiophores and conidia 

 are colourless. Sclerotia were also developed from the Morchella 

 mycelium, hard brown bodies up to 7 mm. in diameter. If grown in 

 a more liquid substratum, a crust of similar texture was formed on the 

 surface. 



Capnodium maximum.* — A fungus (that K. Giesenhagen found on 

 the sori of Polypodium crassifolium in tropical America, was described 

 by him as new, and placed in a new genus, Sorica. He learned later that 

 it had already been described by Berkeley and Curtus as Capnodium 

 maximum. The fungus, however, belongs rather to the Pyrenomycetes 

 than to the PerisporiaceaB, and thus the more recent name is retained. 

 The fungus finds entrance into the leaf either through the young sorus 

 or through wounds at the edge of the leaf caused by the bites of animals. 



Karyokinesis in the Ascomycetes.f — A. Guillermond has investi- 

 gated nuclear division in this group, paying attention chiefly to divisions 

 in the ascus. He has observed in the ascus of Pustularia vesiculosa, 

 Peziza catinus and Ascobolus marginalus, divisions which are of the 

 type described by Harper. In Peziza rutilans, however, the division is of 

 quite a different type, the karyokinesis having no centrosomes but all the 

 characters of nuclear division in Phanerogams. The number of chromo- 

 somes is 12 in P. catinus, 8 in P. vesiculosa, and 6 in P. rutilans ; the 

 generalisation of Dangeard that all the ascomycetes have 4 chromosomes 

 at this stage is thus not supported. The author was unable to solve the 

 problem of the reduction in number of the chromosomes. 



Erysiphe G-raminis4 — In this paper, Part I., E. Salmon discusses 

 the adaptive parasitism of Erysiphe graminis within the genus Bromus. 

 He shows that there exists not only a high degree of specialisation of 

 the fungus, but that each species of the host-plants possesses con- 

 stitutional characters existing concomitantly with the specific morpho- 

 logical characters. As a rule this holds good for all examples of the 

 species wherever grown. In one case he found a biologic form of the 

 host-plant which resisted infection, though morphologically it was 

 exactly similar to the form on which the fungus grew readily. This fact 

 has great economic importance, as pointing to the possibility of breeding 

 races that would be immune to disease. 



In another case, Bromus arduefmensis, the species has been con- 

 sidered by some systematists to possess generic differences that would 

 separate it altogether from this genus. Salmon found that it was 

 markedly susceptible to attacks of the fungi that are parasitic within 

 the genus, and thus its affinity was very strikingly indicated. 



In Part II., he gives an account of his inoculation experiments with 

 the conidia of E. graminis on species of Bromus. The Oidium was taken 

 from several species, and a very large number of experiments were made, 

 with very varying results, according to the affinities and physiological 



* Ber. Deutsch. Bot. Gesell., xxii. (1904) pp. 355-8. 

 t Rev. Gen. Bot., xvi. (1904) pp. 129-43 (2 pis.). 

 X Ann. Mycol., ii. (1904) pp. 255-67, 307-43. 



