48 RESEARCHES ON FUNGI 



range of variation is usually within 10 per cent, of the mean time, 

 on each side of the mean. If development is abnormal, this con- 

 stancy is changed for considerable irregularity : the rate of spore- 

 growth may become much slower than is normal ; all growth may 

 entirely cease ; half-grown or full-sized spores may bend toward 

 one another, touch, and form with the sterigmata a single mass 

 which collapses and sinks downwards on to the basidium-body 

 below ; drops of excessive size may be excreted from the hila of 

 quite immature spores ; and apparently mature spores, with or 

 without the excretion of drops, may not be discharged at all. 

 Owing to abnormalities of the kind indicated, I was unable to make 

 complete observations of the period of spore-development in the 

 following species : Hygrophorus conicus, H. ceraceus, Corticium 

 Solani (Rhizoctonia Solani), and Bolbitius flavidus. Drops of water 

 were not excreted at the hila of the spores at the time they should 

 have been : instead, the basidia collapsed and dragged the spores 

 with them on to the hymenium. Lack of leisure prevented me 

 from making further attempts to observe the completely normal 

 spore-development in these species. 



Discussion of Results. We may now turn to the results of the 

 observations. A glance at the Table shows that there are great 

 differences in the length of time the spores remain on the sterigmata 

 in different species. Thus, in Collybia velutipes, the time is only 

 47 minutes, whereas in Panaeolus campanulatus it is about 7 hours 

 and 30 minutes, i.e. more than nine times as long. In Coprinus 

 sterquilinus the time is about 32 hours, i.e. nearly forty times as 

 long as in the Collybia and nearly four times as long as in the 

 Panaeolus. It is only to be expected that these very diverse rates 

 of spore-development should be correlated with other fruit-body 

 characters. A discussion of these correlations will now follow. 



Mere size is no guide to the rate of spore-development, and one 

 cannot say : the larger the spore, the longer it takes to develop. 

 The small spores of some species actually develop more slowly than 

 the larger spores of other species. Thus the spores of the cultivated 

 Mushroom, Psalliota campestris, which measured 7 25 X 5 6 /* took 

 only about 8 hours to develop from their first origin to discharge, 

 whereas the larger spores of the Fairy Ring Fungus, Marasmius 



