348 Transactions British Mycological Society. 



ON THE BIOLOGY OF PANUS STYPTICUS. 



With Plate IX. 



By Marie E. M. Johnson. 



Panus stypticus Fr., so called because of its remarkable astrin- 

 gent taste, is found on old logs of fir, alder, beech, oak, hazel, 

 birch, chestnut, etc. throughout the year. It grows best in 

 damp situations, but too much moisture is injurious. When a 

 log infected with this fungus was brought into a garden in the 

 vicinity of some iron and chemical works, the sporophores be- 

 came discoloured, lost their usual fresh appearance, and gener- 

 ally became unhealthy; the young sporophores almost ceased to 

 grow, and no new ones appeared, although the log was continu- 

 all}^ moistened. The smoky atmosphere, sometimes charged with 

 poisonous gases, was evidently quite unsuitable for its growth. 

 It seemed at first as if the damage were due to frost, rather than 

 to the unsuitable black-country atmosphere, but even when the 

 log was kept in a more sheltered situation, and covered up during 

 severe frosty nights, no new sporophores appeared, suggesting 

 that frost could not have been the sole cause of their non- 

 appearance, though it may have been the cause of a retarda- 

 tion of growth. Later, when the infected log was removed to a 

 clearer atmosphere, young fresh-looking sporophores quickly 

 appeared. Moreover, a large piece of wood, which had previously 

 been broken off from this infected log and kept in a country 

 district, produced sporophores which were unaffected by frost. 



Panus stypticus is one of the many fungi eaten by slugs, which 

 on discovering the whereabouts of an infected log, cause the 

 rapid disappearance of young sporophores and bite large pieces 

 out of mature ones, leaving only their slimy trail to account for 

 the damage. It is possible that slugs may be active agents in 

 the dispersal or even the germination of the spores. 



Spores and their Germination in Hanging Drop Cultures. The 

 spores are colourless, oval, and apiculate, having a size of 4/x 

 X 3/Lt. They germinate readily in rain-water, 5 per cent, glucose, 

 10 per cent, gelatine, malt-wort extract, and various other 

 media, and even spores which had been dried for five days in the 

 atmosphere of the laboratory germinated after 20 hours. 



Bacteria are said to assist germination but according to ob- 

 servations made on hanging drop cultures, their presence was 

 not beneficial to the germination of these spores. 



Wood Block Cultures. Small pieces of sterilised wood infected 

 with basidiospores in an infection chamber, were placed in glass 

 cylinders (7 inches long) and plugged with cotton wool which 



