COPRINUS STERQUILINUS 243 



beautiful refinement in the organisation of the hymen ium ; for, 



obviously, it is correlated with the crowding together of the 



dimorphic basidia and serves to prevent the spores of the short hasidia 



colliding with, and adhering to, the spores of the long hasidia during 



their discharge. Here again, we have clear evidence of the high 



efficiency with which the fruit-body of a Coprinus performs it one 



great function of producing and liberating spores. 



Fig. 105 (p. 249) represents a vertical transverse section through 



the lower part of a gill corresponding to the surface view of Fig. 104 



and allows us to study the zone of spore-discharge from a new angle. 



The spores about to be discharged are represented with arrows in 



front of them, the arrows indicating the directions in which the 



spores will travel away from the hymenium. Here, as we have 



seen in the surface view, the sub-zone of spore-discharge for the long 



basidia, 6^, lies at a higher level than the sub-zone for the short 



basidia, h.^. Thus, on the left-hand side of the figure, the long 



Fig. lOir—cont. 



space. There are two sub-zones: 6j — 6j, tlie zone of spore-discharge for the 

 long basidia ; and b^. — b^, the zone of spore-discharge for the short basidia. 

 In fej — by, the four spores of each long basidium are shot off tlieir sterigmata 

 in succession, so that in this zone some of the long basidia have three spores 

 left upon them, some two, and some one. A few seconds before a spore is 

 shot away, a small drop of water is excreted at the top of the sterigma. This 

 drop is represented as projecting toward the axis of the basidium beneath 

 many of the spores, e.g. in the basidium w. In the sub-zone 6^ — 6j, none of 

 the short basidia have shed their spores. In the sub-zone of spore-discharge 

 for the short basidia, 62 — b^, the long basidia, I, no longer bear any spores ; 

 but they can be distinguished by their heavier shading and by their vacant 

 sterigmata. The short basidia only are discharging spores. Some of them 

 have three spores on, some two, and some one. Just before tlie discharge of 

 each spore, a drop of water similar to that already described in connection 

 with the sub-zone 6j — ^6^, is excreted at the top of each sterigma, e.g. as at v. 

 (3) c — c, the zone of basidia which have shed all their spores. Here botli long 

 and short basidia, normally, have shed all their spores. One basidiimi, i, still 

 has four spores upon it, but these are immature and are destined eventually 

 to join the wasted spores at the extreme gill-edge. I, a long basidium ; s, a 

 short basidium ; p, a paraphysis. (4) d—d, the zone of autodigestion. The 

 basidia and paraphyses are becoming indistinct. The walls are breaking down 

 into fine granules. The spores yn and n failed to be discharged at tlie proper 

 time and are destined to join the other wasted spores at the extreme gill- 

 edge. I, a long basidium ; s, a short basidium. (0) c — e, the liquid film at 

 the gill-edge containing the products of autodigestion and the spores which, 

 for one reason or other, failed to be discharged in a normal manner. At the 

 top of this zone, the collapsed basidia can still be dimly traced by rows of 

 granules. Deeper down in tlie zone, the products of autodigestion are more 

 homogeneous. At the gill-edge are a large number of undischarged or 

 wasted spores. Some have a normal appearance ; while others are above 

 or below normal size, or are colourless, or not completely pigmented. They 

 form but a small percentage of the whole number of sijores. As the zone 

 rises, it will add to itself the spores m and n and those at i. The scale on 

 the right-hand side of the Figure shows the dimensions of every part. 



