RATE OF DEVELOPMENT OF INDIVIDUAL SPORES 53 



on the one hand, species of the genera Psalliota, Stropharia, 

 Panaeolus, and Coprinus, and, on the other hand, species of 

 Collybia, Marasmius, Armillaria, Russula, and Hygrophorus, is 

 marked. Illustrations of this difference will be given subsequently 

 in this and the next volume. 



In Lepiota procera, the well-known Parasol Fungus, the spore- 

 bearing basidia are just as crowded as in a Panaeolus. Moreover, 

 the spores have thick walls. Fayod, 1 in an illustration, has clearly 

 shown the thick inner endospore lying inside the exospore. This 

 fungus is therefore exceptional in the Leucosporae. I suspect that 

 the time required for development of its individual spores will be 

 found to be much longer than in most Leucosporae, such as species 

 of Collybia, Marasmius, etc. 



The very long period of time required for the development of 

 individual spores of Coprinus sterquilinus, namely, 32 hours, calls 

 for some special remarks. As will be made clear in a subsequent 

 Chapter, there are two main types of fruit-body mechanism for the 

 production and liberation of spores : the non-Coprinus type and 

 the Coprinus type. In the former, on any small area of the 

 hymenium (e.g. 1 square mm.) there is a series of successive 

 generations of basidia which bring their spores to maturity in 

 succession ; so that, although spore-production for an individual 

 basidium takes but a short time not more than a few hours 

 yet spore-production is continued for several days. In the latter, 

 on the other hand, on any small area of the hymenium, all the 

 basidia produce their spores practically simultaneously and the 

 basidia are extremely crowded owing to the occurrence of 

 dimorphism. The very slow rate of development of individual 

 spores in Coprinus sterquilinus seems to me to be correlated with 

 the simultaneous development of the spores and the extreme 

 crowding of the basidia. Doubtless, in many of the smaller 

 Coprini, the rate of spore-development is much less than 36 hours ; 

 but I have reason to suspect that a very slow rate characterises 

 the whole genus. Coprinus sterquilinus has very large spores, 

 20 X 11 p, the largest which I have met with during the examina- 

 tion of nearly thirty species of Coprinus. It may therefore be 

 1 M. V. Fayod, loc. cit., PL 6, Pig. 9. 



