COLLYBIA VELUTIPES 493 



Polystictus versicolor, and P. hirsutus, all continue to develop and 

 discharge their spores at 0° C, while Brooks and Hansford ^ have 

 recently demonstrated that several moulds, such as Cladosporium 

 herbarum— the Black Spot Fungus, Torula botryoides, Sporotrichum 

 carnis, Penicillium expansum, and Thamnidiiim spp., which live on 

 frozen meat and cause its deterioration, are able to grow at a 

 temperature of from -6° to 0° C' Since, as we have seen above, 

 Collybia velutipes produces thin spore-clouds at a temperature of 

 34° F., it is possible, although no experiment has yet been made to 

 decide the matter, that its basidia continue to develop and discharge 

 spores very slowly even when the air by which they are surrounded 

 has been cooled to 32° F. 



1 F. T. Brooks and C. G. Hansford, " Mould Growths upon Cold-store Meat " 

 Trans. Brit. Myc Soc, vol. viii, 1923, pp. 113-141. These authors in their Summary 

 say : " Some strains of Cladosporium herbarum will develop from spores at a tem- 

 perature of — 6° C. and will give rise to considerable growths, including conidiophores, 

 under prolonged cold-storage conditions. Torula botryoides, Sporotrichum carnis, 

 Penicillium expansum, and Thamnidium spp. sometimes develop slightly at this 

 temperature, but readily at 0°C., and it is probable that they grow appreciably 

 between these two temperatures." For a previous report on the conditions oi 

 growth of the Black Spot Fungus, vide F. T. Brooks and M. N. Kidd, Black Spot of 

 Chilled and Frozen Meat, Special report 6, Food Investigation Board, Dept. Sci. and 

 Ind. Research, London, 1921. 



2 A French worker, C. Bidault, who has studied the moulds occurring on frozen 

 meat, states ("Sur les Moisissures des Viandes Congelees," Comp. rend. soc. biol., 

 T. LXXXV, 1921, p. 1017), without giving details of his experiments, that Chaeto- 

 stylum Fresenii {= Thamnidium chaetocladioides) and Hormodendron cladosporioides 

 { = Cladosporium herbarum) will grow slightly at — 10° C, and that other species 

 wiU grow between - 6° C. and 0° C. Cited from the paper of Brooks and Hansford 

 loc. cit., p. 114. 



