The Reactions of the Fruit-Bodies of Lentinus 
lepideus, Fr., to External Stimuli. 
BY 
A. H. REGINALD BULLER, D.Sc, PhD., 
Professor of Botany at the University of Manitoba. 
With Plates XXIII, XXIV and XXV. 
T HE fruit-bodies of Lentinus lepideus were grown upon rotting paving 
blocks obtained from the streets of Birmingham. The destruction of 
the pavement by the Fungus and the life-history of the latter will be 
described in another paper 1 . 
Lentinus lepideus belongs to the Agaricini. Its fruit-bodies are 
coriaceous, slow in growth, and live for some weeks. They are very 
variable in form, and frequently monstrous. Their development on such 
a convenient substratum as wooden paving blocks afforded me an oppor- 
tunity of investigating their relations to external stimuli. 
Sachs 2 showed that the stipes of a number of Agaricini are negatively 
geotropic, and that the gills are positively geotropic, while the pilei take up 
a horizontal position. Brefeld 3 studied the effect of light on species of the 
genus Coprinus. I have endeavoured to give as complete an account as 
possible of the various reactions to stimuli of a single gilled Fungus, 
a hitherto uninvestigated species growing upon wood, and to explain the 
reactions on oecological grounds. 
Rotting blocks were obtained from a street pavement, and placed in 
a large damp- chamber. About fourteen days afterwards a thin snow-white 
mycelial layer grew out on the surfaces of the blocks, especially on surfaces 
exposed by the breaking of the wood. After about two days more, small 
white papillae — the beginnings of the fruit-bodies — began to develop upon 
the mycelium (Figs. 6, 13, and 19). 
The papillae often arise in considerable numbers side by side (Fig. 6). 
They develop into conical protuberances, the further history of which 
depends mainly on the condition of light. 
1 In Joum. of Economic Biology, Vol. I, pt. i, Oct. 1905. 
2 Experimentalphysiologie, 1865, p. 93; also Hofmeister, Ueber die durch Schwerkraft bestimm- 
ten Richtungen von Pflanzentheilen, Jahrb. fiir wiss. Bot., Bd. iii, 1863, pp. 92 and 93. 
3 Botanische Untersuchungen iiber Schimmelpilze, Heft iii. Basidiomycetes, I. 1877, pp. 87-97. 
[Annals of Botany, Vol. XIX. No. LXXV. July, 1905.] 
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