NOCTURNAL SPORE-DISCHARGE 



475 



(2) One needs a source of light. I have obtained good results 

 with an electric hand-lamp, such as is made use of in garages, etc. 

 This hand-lamp (Fig. 196) is merely an upright rectangular wooden 

 box (2*5 X 3'5 X 7*5 inches), containing a storage battery and a 

 filament, having a leather 

 handle above, and emitting 

 its hght through a laterally 

 situated plano-convex lens. 



(3) One also requires a dark 

 background against which one 

 may see the illuminated spores. 

 To obtain this, one works by 

 night instead of by day. At 

 night, especially during the 

 autumn and winter months, a 

 dark or even deep black back- 

 ground of shadows may be 

 readily procured. 



(4) The temperature must 

 not be below freezing-point ; 

 for, if it is, spore-discharge in 

 all probabihty will have ceased, 

 at least temporarily. As a 

 rule, the warmer the air, the 

 more rapidly does a fruit-body 

 liberate its spores. Warm 

 weather is therefore to be 

 preferred to cold. 



(5) Lastly, the wind must 

 not be too strong, for a strong wind disperses the spores so 

 rapidly that one may find it difficult or even impossible to perceive 

 them. In windy weather one should screen the fruit-bodies from the 

 wind with an overcoat. The best results are obtained on still nights. 



Granted that the conditions for making observations are 

 favourable, let us go out together on a little nocturnal expedition. 

 We are in England, the month November. Of late it has been mild 

 and even now the thermometer registers 45° F. The night is dark 



Fig. 196. — The electric hand-lamp'used for 

 noctvirnal observations on the spore - 

 discharge of Agaricineae. Reduced 

 to about |. Diameter of lens, 2-25 

 inches. 



