PSALLIOTA CAMPESTRIS 



379 



subjects the gills to a lesser and more equal strain during the 

 expansion of the pileus than the concentric one. 



(1) As a pileus of a Mushroom opens out, its periphery moves 

 away from the stipe and upwards about the stipe apex (Fig. 134). 

 During this movement, the median planes of the lamellae remain 



FIG. 136. Amanita rubescens. The same fruit-body as that shown in 

 Fig. 135, but one day older. The top of the pileus is now flat. The 

 expansion of the pileus since the previous day has raised the gills 

 and inclined them upwards, thus giving to the wind a better chance 

 of carrying away the spores. Photographed at Four Oaks, War- 

 wickshire, by J. E. Titley. About -3- natural size. The pileus was 

 4 inches in diameter. 



vertical, so that the hymenium on their sides continues to look 

 slightly downwards. An upward movement of the whole pileus- 

 periphery does not therefore seriously affect the escape of the 

 spores which are being discharged from the basidia. But let us 

 suppose that the lamellae in the closed pileus were to arise on the 

 base of the pileus-flesh in the form of concentric bands. Then, as 

 the pileus expanded, the median gill-planes would constantly alter 

 their inclination to the vertical, and they could not take up their 

 final vertical positions until the pileus-flesh had ceased to move. 



