78 SUMMARY OF CURRENT RESEARCHES RELATING TO 



many of the Valsece, among the forms that may become parasitic in 

 favourable surroundings. 



Study of Fungi imperfecta* — H. Klebahn is continuing his re- 

 searches in this branch of mycology. He has succeeded in demonstrating 

 the connection between Marssonia juglandis and the ascomycetous form 

 Gnomonia leptostyla, both found on walnut leaves. Klebahn sowed the 

 spores of Gnomonia on young leaves of the host-plant, and produced 

 the Marssonia form. Intermixed with the rather large two-celled 

 Marssoyiia spores he found small one-celled spores that have been 

 wrongly described as a separate fungus under the name Leptofhyrium 

 juglandis. He also made gelatin cultures of the Marssonia spores, 

 which he describes. The perithecia of the Gnomonia fruit carry the 

 fungus over the winter, and to stamp out the disease it is only necessary 

 to destroy the leaves in autumn or before the spring vegetation is 

 formed. 



Sexuality and Development of Ascomycetes. — Two papers on this 

 subject have appeared recently. The first, by E. J. Welsford,| contains 

 an account of the development of Ascobolus furfurascens. In this fungus 

 the earliest stages show a scolecite of 6-10 usually similar uninucleate 

 cells, which by division rapidly become multinucleate. The fourth cell 

 from the end becomes larger than the others, and forms the ascogenous 

 cell. The protoplasm and nuclei from the other cells of the scolecite 

 pass into the ascogenous cell, where they fuse in pairs and enter the 

 ascogenous hyphae, which rise from that cell. These hyphee grow out, 

 bend over in the usual characteristic fashion, and form the asci. The 

 author considers that the nuclear fusions in the ascogenous cell repre- 

 sent a reduced sexual process. 



The second paper, by H. C. Fraser,J describes the sexual process in 

 Lachnea stercorea, which the author sums up thus : (1) The archicarp 

 of Lachnea stercorea consists of several cells, and terminates in a large, 

 multicellular archegonium. (2) From the ascogonium a trichogyne, 

 which is at first unicellular, but eventually consists of four, five, or six 

 ccenocytic cells, grows out. Its terminal cell is much larger than the 

 others, and may become continuous with the antheridium. (3) The 

 antheridium, which is not always fully developed, is a unicellular cceno- 

 cytic sac ; its origin could not be traced with certainty. (4) The male 

 nuclei do not reach the ascogonium, but fertilisation of a reduced type 

 occurs, the female nuclei fusing in pairs. (5) Ascogenous hyphs, into 

 which the fused nuclei pass, grow out from the ascogonium, and asci 

 are formed, by the usual method, at their tips. (6) Lachnea stercorea 

 is intermediate, with regard to its sexuality, between Pyronema con- 

 fiuens, on the one hand, and Hiimaria granulata on the other, and with 

 regard to the organisation of its trichogyne, between Pyronema and 

 certain of the Pyrenomycetes. Experiments were also made on spore 

 germination in this species. They were treated with digestive fluids or 

 with dung extract, and germination took place in about fifty hours 



* Zeitschr. Pflanzenkr., xvii. (1907) pp. 223-37 (1 pi. and 2 figs.), 

 t New Phvtologist, vi. (1907) pp. 156-61 (1 pi.). 

 I Ann. of Bot., xxi. (1907) pp. 349-60 (2 pis.) . 



