On the Biology of Panus stypticus. M. E. M. Johnson. 351 



Reactions of Sporophores to [a) Light. Logs bearing young 

 sporophores having an average height of about 2 mm. were 

 kept in darkness for four months under suitable conditions of 

 humidity. At the end of this period examination showed no 

 increase in the size of tlie fruit bodies, in fact some had become 

 smaller and looked very withered. The majority of the fruit 

 bodies were about one and a half mm. in height and had de- 

 veloped no pilei; others had a stipe of about 2 mm. in length 

 and a pileus about half a mm. across. Even in partial darkness 

 the sporophores which appeared had abnormal stipes and small 

 or no pilei. Yet darkness appeared to favour the growth of 

 mycelium. 



[b] Gravity. A branch bearing a few small fruit bodies was 

 attached to a clock clinostat and rotated on a horizontal axis, 

 a continuous and constant supply of moisture for the fruit 

 bodies being arranged: a control experiment was kept. The 

 branch on the clinostat was rotated once every 20 minutes. 

 For four months the experiment was continued but normal 

 sporophores were never formed. New tiny pyramidal masses 

 appeared which quite quickly developed pilei: the stipes of 

 these fruit bodies were shorter in comparison with the breadth 

 of the pilei than on normally grown fruit bodies ; gills soon ap- 

 peared and the sporophores matured quickly. Some of the 

 stipes became curiously swollen and without exception the 

 fruit bodies expanded their pilei at right angles to the axis of 

 revolution so that the gills developed horizontally instead of 

 assuming the normal vertical position (fig. 5). 



Thus it appears that both light and gravity influence the de- 

 velopment of the sporophores. 



Paiiiis stypticus is a xerophytic fungus, for sporophores after 

 being dried for six months or longer will revive when moistened 

 and shoot off spores capable of germination. 



The mycelium also of this fungus retains its vitality after 

 receiving little or no moisture for many months. 



In conclusion I wish to express my thanks to Dr Jessie S. 

 Bayliss Elliott for the valuable assistance she has given me in 

 many ways during the course of this study. 



SUMMARY. 



1. The sporophores of Panus stypticus can withstand frost 

 and so can be cultivated out of doors in winter months. A 

 sporophore takes about three months in developing. 



2. The spores germinate readily in suitable media, and wood 

 block cultures when given a favourable supply of light and 

 moisture produce sporophores in the course of six or seven weeks. 



