PANAEOLUS CAMPANULATUS 309 



with it. Now, as I have observed when watching the discharge 

 of spores with the horizontal microscope in the manner already 

 described, 1 it sometimes happens that the spores on a basidium 

 are not shot off when the drops below them have attained their 

 normal size, but the drops increase in size (D and E) until they 

 finally meet and fuse together (F). The four spores, without being 

 detached from their sterigmata, are drawn nearer together owing 

 to the pull exercised upon them by surface tension (F). The drops 

 may go on enlarging so that the spores are pushed further apart 

 than they are normally (G and H). The excretion of water by 

 the sterigmata then ceases and the drop gradually evaporates. 

 As the drop diminishes in size, the four spores are drawn together 

 so that they come in contact with one another (I). A few minutes 

 after the spores have met, the basidium to which the spores belong 

 contracts in length, its end becomes concave, and its sterigmata 

 are drawn into the concavity. It thus comes about that the four 

 spores are dragged down to the general level of the hymenium, 

 where they remain until the decay of the pileus sets in (J). The 

 loss of spores owing to over-enlargement of the water-drops in 

 the manner described was observed a great many times on the gills 

 of Panaeolus campanulatus when they were being viewed with the 

 horizontal microscope, but I have also observed the phenomenon 

 on the gills of several other Hymenomycetes. 



Sometimes, after two or three of the spores of a basidium have 

 been successfully discharged, the remaining spores stay on their 

 sterigmata until the basidium collapses. At the necks of the 

 sterigmata belonging to the spores which are to be wasted no 

 drops of water appear. In these cases the failure of the spores 

 to leave their sterigmata may be connected in the first place with 

 the failure in the excretory activity of the sterigmata. I have 

 now watched the discharge of many hundreds of spores of different 

 Hymenomycetes with a sufficiently high power of the microscope, 

 but never once, since I began to pay attention to the excretory 

 phenomenon, have I ever seen a spore shot away without a water- 

 drop being formed, a few seconds before discharge, at the hilum 

 of the spore where this is attached to the neck of the subjacent 

 1 Pp. 260-263, also Figs. 91 and 92. 



