2i8 RESEARCHES ON FUNGI 



from full size, to the fully pigmented condition is at least twelve 

 hours ; and, after the spores have become fully pigmented, another 

 twelve hours may elapse before spore-discharge takes place. The 

 duration of the period from the beginning of the division of the 

 fusion-nucleus to the discharge of the last spore is about thirty-six 

 hours. 



The average length of time taken for the development and 

 ripening of an individual spore from the moment the spore appears 

 on the sterigma as a tiny rudiment until the moment of discharge 

 is a little less than one hour in CoUybia velutipes and Dacryomyces 

 deliquescens ; between one hour and one hour and thirty-one minutes 

 in Collybiafusipes, Marasmius oreades, Exidia albida, Calocera cornea, 

 Armillaria mellea, and CoUybia radicata ; and between five and eight 

 hours in Stropharia semiglobata, PsalUota campestris, and Panaeolus 

 campanulatus ; but in Coprinus sterquilinus it is about thirty-two 

 hours .1 The relatively great length of the time required by our 

 Coprinus for spore-development and spore-discharge appears to be 

 due in part to the very large size of the spores, but largely to the fact 

 that all the basidia on any small area of the hymenium develop 

 simultaneously instead of in successive groups. It is also not im- 

 probable that the spores on any part of a gill are completely ripened 

 and prepared for discharge some mirmtes or possibly hours before 

 the upward-moving zone of spore-discharge brings with it the 

 stimulus for discharge, provision thus being made for a margin of 

 safety comparable with that most people allow when thej^ go to 

 a railway station to catch a train. 



The Spores. — The spores of Coprinus sterquilinus are circular in 

 outline when seen from above (Fig. 86, p. 202), which shows that 

 their breadth and thickness are equal. They are much longer than 

 they are broad or thick, for they are oval in outline (Fig. 92) and 

 measure 20-22 by 11-12 ^.^ They are by far the largest spores 



1 Vol. ii, 1922, pp. 44, 54. 



2 These measurements were made from the spores of a single fruit-body. Mr. 

 W. F. Hanna, working in my laboratory, has measured the length of 100 spores of 

 a series of fruit-bodies of Coprinus sterquilinus, each derived from a monosporous 

 culture, and has found that the average length of the spores varies in different 

 fruit-bodies from about 15 /i. to 22 /a. A full report of this work will be published 

 shortly. 



