388 SECTIONAL TRANSACTIONS— K. 



Prof. Dame Helen Gwynne-Vaughan and Mrs. Williamson. — Varia- 

 tions in the formation of the fruit in the Ascomycetes. 



The fructification of the Ascomycetes may be homothalhc or hetero- 

 thallic in origin ; it may originate in a normal sexual process, or the sexual 

 apparatus may have partly or wholly disappeared. In either case nuclei 

 formed by the union of those from one or of two complementary mycelia 

 may pass into the ascogenous hyphae. The sheath may be formed from 

 branches of a single mycelium, from branches originating separately from 

 two mycelia, or from branches derived from a region where two mycelia 

 have fused. Variations are present in the types of gametangia and of 

 ascogenous hyp has. 



Mr. C. G. C. Chesters. — An interesting Phycomycete associated with 

 a diseased condition of Antirrhinum. 



The fungus described in this paper was obtained from the roots 

 and stems of diseased Antirrhinum seedlings. The actual disease was 

 caused either by Rhizoctonia Solani or by Phyllosticta Atitirrhifii, and this 

 fungus was present as a secondary organism. Later it was obtained in 

 quantity from nursery soil. Its exact systematic position is doubtful, but 

 there is evidence that it occupies a position close to the Zygomycetes, in 

 that its ' resting-spore ' is formed by the conjugation of two hyphal branches. 

 The mature ' resting-spore ' is somewhat similar in appearance to that of 

 one of the higher members of the Chytridiales, but so far no motile stage 

 has been observed in the life-history. The normal means of reproduction 

 is by the germination of intercalary spores. The mycelium produced in 

 culture is white and forms a thick skin on the surface of the medium, from 

 which dense aerial hyphae arise. These bear numerous intercalary spores. 

 Within the medium and in the neighbourhood of the inoculum nests of 

 branched hyphae give rise to structures which are here termed ' resting- 

 spores.' When mature each of these consists of a thick -walled terminal 

 spore borne on a thin-walled swollen stalk, which is attached to the mycelium 

 by a branched hypha. So far the resting-spore has never been observed to 

 germinate. The fungus grows well as a saprophyte in soil and can infect 

 weakly or etiolated Antirrhinum plants. 



Mr. A. H. Campbell. — Black lines in timber caused by Xylaria polymorpha. 



A preliminary attempt has been made to classify the black lines associated 

 with wood-rots into groups, in order to provide a basis for research and to 

 facilitate the statement of results. 



The black lines formed in the substratum by the genera Nummularia, 

 Ustulina, Hypoxylon, Daldinia and Xylaria comprise such a group. 



The black lines formed by Xylaria polymorpha have been investigated 

 morphologically and culturally and their actual formation has been observed. 

 As a result the suggestion is made that the black lines are the marginal 

 zones of entostromata in the substratum comparable to those occurring in 

 Diaporthe. 



An account is given of a Xylaria polymorpha black line superimposed 

 upon the zone line formed by the attack of Fames applanatus on beech wood. 



Semi-popular lecture by Dr. E. J. Butler on Tropical plant diseases, their 

 importance and control. 



