620 Buller-—The Function and Fate of the 
at the gill-edge (PI. L, Fig. 7). These five zones keep their relative distances 
apart unaltered. They gradually move upwards, so that in the course 
of about forty*eight hours they involve the whole of each gill (cf. PI. L, 
Figs. 1-4). 
The discharge of the spores from the basidia in Coprimis atramentarius 
takes place in a manner similar to that which I have described for other 
Coprini and for the Hymenomycetes generally. The four spores of each 
basidium are violently propelled more or less perpendicularly outwards 
from the hymenium into the adjacent interlamellar space. The four spores 
of each basidium leave the sterigmata one by one, and are not all dis¬ 
charged together. The discharges can easily be watched if one lays a piece 
of a gill, like that shown in PI. L, Fig. 7, in a closed compressor cell (where it 
is protected from undue loss of moisture), and looks down upon it from 
above. The spores can then be seen leaving the basidia in the zone of 
spore-discharge. Some of the basidia will be seen to have four spores upon 
them, some three, some two, some one, and some none at all. 
In my previous researches I 1 have shown that the spores of the Mush¬ 
room, of Poly poms squamosus , and of Coprinus plicatilis are shot forward in 
almost a straight line into the interlamellar spaces to a distance of about 
o-io mm., and that the horizontal motion is very rapidly brought to an end 
owing to the resistance of the air. In still air, in consequence of this 
resistance and of the attraction of gravitation, a spore, when nearing the 
end of its horizontal flight, describes a sharp curve and falls vertically 
downwards. I have called the peculiar trajectory of a spore between the 
gills the sporabola. 2 By using methods which have been described in 
detail elsewhere, I have proved to myself that the spores of Coprinus atra- 
mentarius have a trajectory similar to that of Coprinus plicatilis and other 
Coprini, and that the horizontal distance of discharge is of the order of 
0-05 mm. Unfortunately an exact determination of this distance could not 
be made owing to the limited time during which living fruit-bodies were at 
my disposal. On the assumption that 0-05 is the average distance of dis¬ 
charge of spores shot out perpendicularly from the hymenium, I have 
indicated the sporabolas of a few spores in the zone of spore-discharge 
in the semi-diagrammatic drawing in PI. LI, P'ig. 19. It is certain that the 
spores are shot forward to such a distance from the basidia that they fall 
downwards somewhere near the middle of the interlamellar spaces. I have 
already pointed out that the advantage of violent spore-discharge lies in the 
fact that thereby the adhesive spores are prevented from coming into con¬ 
tact with one another or with the gill-surfaces during their fall. 
The cystidia are so large and numerous that, if they persisted until the 
zone of auto-digestion reached them, they would form a serious hindrance to 
the escape of the spores from between the gills. They would block up 
1 A. H. R. Buller, Researches on Fungi, pp. 141 and 142. 2 Ibid., 1 . c., p. 185. 
