266 RESEARCHES ON FUNGI 



its course was run in about eight hours. To summarise for a 

 single basidium, the time was occupied as follows : 



(1) Finishing the development of the sterigmata 



after discharge of the spores on adjacent 

 first-generation basidia, about , . 45 minutes 



(2) Developing spores from their origin to full 



size . _...... . . . . . 45 minutes 



(3) Full-sized spores remaining colourless and 



receiving contents from the basidium . 90 minutes 



(4) Full-sized spores turning brown and finally 



black . . . ... . . . 90 minutes 



(5) The further maturing of the spores (and 



possibly the further accumulation of 

 brown pigment), ended by violent spore- 

 discharge, about . . . . . 210 minutes 



Total time about 8 hours 



We are now in a position to explain the rule of mottling already 

 mentioned (p. 252), namely, that when a gill of Panaeolus cam- 

 panulatus is observed with the naked eye the dark areas always 

 exceed the light in extent. From the data obtained with the 

 microscope and given above, we can divide the eight hours occu- 

 pied by the hymenial area in the development of the second 

 generation of spores into three subdivisions as follows : 



(1) A white period of 3 hours, at the end of which the spores 



are of full size but still colourless. 



(2) A brown or intermediate period of 1 5 hours, during which 



the spores turn brown and finally black, and 



(3) A black period of 3-5 hours, during which the spores remain 



black, ending with spore-discharge. 



Now to the naked eye, as soon as the spores begin to turn brown, 

 they come to have a very dull appearance. On looking at the 

 hymenium without the microscope, one therefore naturally divides 

 the areas into light and dark, the dark including not only those 



