50 RESEARCHES ON FUNGI 



of receiving too little water for their development. Lepiota procera 

 is a typical white-spored species growing on the ground ; but it 

 has thick walls to its spores. In this fungus I found that the 

 time taken for spore-development was more than two hours ; but, 

 owing to an unavoidable interruption, I was unable to com- 

 plete the investigation. Another terrestrial white-spored species 

 examined was HygropJiorus ceraceus. Unfortunately, although 

 its spores apparently grew to maturity in a normal manner, their 

 discharge was not effected : they were dragged down on to the 

 hymenium by their basidia when these collapsed. However, I 

 have little doubt, from the observations made, that the period 

 of spore-development up to the moment of discharge in this species 

 is about 3 hours and 30 minutes. HygropJiorus conicus was also 

 found to develop its spores very slowly, and I suspect that the 

 Hygrophori, all of which are characterised by possessing fruit- 

 bodies with an extraordinarily waxy consistence, develop spores 

 more slowly than the species of Collybia, Marasmius, and Armillaria. 



Proceeding down the list given in the Table we find that from 

 Pluteus cervinus onwards the time taken for spore-development is 

 relatively long. All these remaining species have spores which 

 either are coloured or are provided with irregular walls. Pluteus 

 cervinus and Nolanea pascua both have pink spores and take 3 

 hours 20 minutes and 4 hours 15 minutes respectively to develop 

 their spores. In the former species the spore- walls are smooth 

 whereas in the latter they are more complex, for they become 

 polyhedral. Perhaps this added complexity in the Nolanea 

 accounts for the fact that this species takes about an hour longer 

 than the Pluteus to develop its spores. 



Russula cyanoxantha has spores which are colourless but possess 

 warted walls. Here again, the warting of the walls seems to be 

 a factor increasing the time required for spore-development, which 

 in this case amounts to 5 hours and 10 minutes. 



The remaining species in the Table have highly pigmented 

 spore-walls. Stropharia semiglobata, with brown-purple spores, 

 takes 5 hours and 40 minutes for spore-development. Psalliota 

 campestris (the cultivated form), also with brown-purple spores, was 

 observed to take 8 hours ; but, possibly, with fresher material than 



