308 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



eluded that the fungus could not penetrate the older parts of the plant. 

 He found on comparison with other species that this Feronospora was 

 closely aUied to P. Dipsaci. 



Study of Rhytisma acerinum.* — Karl Miiller has made a culture 

 study uf this fungus whicli gives rise to the familiar black spots on the 

 leaves of the plane tree. He has established several biological races on 

 the different species of plane trees. Infection takes place generally by 

 the stomata on the under side of the leaves. Miiller gives many details 

 as to time of infection, the maturing of the sclerotia, and the form and 

 ejaculation of the spores. He does not consider that the trees are very 

 seriously injured. 



Study of Gymnoascus.t — A. Sartory and G. Bainier followed the 

 development of Oymnoascus confluens sp. n. The filaments that form 

 the receptacle are extremely delicate, and the centre is occupied by a 

 mass of asci. In culture, the spores germinate quickly and form a thick 

 layer of colourless hyph^e. After a month or so, red or orange spots 

 appear on the mycelial mass, which consists of crowded asci. The first 

 stages of ascus formation w^ere also observed : certain mycelial filaments 

 produce laterally and fairly close together, short special branches, which 

 bend C)ver at the tops, then form a spiral of very few turns. The 

 filament forming the spiral becomes septate and each cell enlarges, 

 rounds off, and becomes an ascus. The small group of asci thus formed 

 may remain isolated, but more frequently a number of groups become 

 associated. They take various shades of orange or red as they mature. 

 Chlamydospores are also occasionally formed. 



Life-history of Ascocliyta on some Leg-uminous Plants. J — R. 

 E. Stone has made a special study of some species of Ascochyta, that 

 grow on leguminous plants. He has summed up the results of previous 

 writers, and gives an account of his own discoveries. Ascochyta Pisi is 

 first described. It infects the seed and is thus carried over to new crops 

 of the host plant. On the stems and pods of the garden-pea, attacked by 

 the Ascochyta^ Stone collected in the autumn an ascigerous fungus Sphse- 

 reiki pinocles ; and concluded that the two fungi were members of the 

 life-cycles of the same species as they are very often found intimately 

 associated ; Ascospores germinated in nutrient media produced an Asco- 

 chyta, agreeing in all particulars with cultures derived from Ascochyta 

 Pisi ; Ascochyta developed from the ascospores of the Sphserella in pure 

 cultures, infects the pea and produces fungal spots from which the 

 Ascochyta can be re-isolated ; and lastly Sphserella ascospores directly 

 infect the pea plant, reproducing Ascochyta. 



Another species taken from Vicia villosa was experimented with and, 

 from a series of observations and from cultures, was found to be asso- 

 ciated similarly with Sphserella Vicise. He found further that the two 

 forms were identical with the Ascochyta and Sphserella on the pea. that 

 is, with S. pinodes. Stone places the fungus in the genus Myco sphserella. 



* Centralbl. Bakt., xxxvi. (1912) pp. 67-98 (4 pis. and figs.), 

 t C.R. Soc. Biol. Paris, Ixxiv. (1913) pp. 498-9. 

 X Ann. MycoL, x. (1912) pp. 5G4-92 (2 pis.). 



