GENERAL SUMMARY 573 



glycogen disappears completely both from the basidium-body and the 

 spores. 



The growth of a spore to full size and its ripening were found to take 

 about 32 hours, a much longer period than in most Hymenomycetes. 



As a rule, the more rounded side of a spore is directed downwards 

 when the spore is falling through the air both when the spore is fully 

 turgid and when it has become more or less boat-shaped owing to loss 

 of water and contraction. In consequence, a spore usually settles on its 

 more rounded side. This more rounded side bears a colourless concavo- 

 convex wall-meniscus which is very adhesive and serves to attach spores 

 to grass, etc., so firmly that the spores cannot be dislodged either by 

 violent winds or by heavy rain-storms. The firm adherence of the 

 spores to grass and other herbage is important in that it greatly increases 

 the chance of the spores being swallowed by horses and other herbi- 

 vorous animals, and therefore also the chance of the spores finding their 

 way into dung in which they may germinate. 



In the general zone of spore-discharge the long basidia shoot away 

 their spores before the short basidia beyond which they project. This 

 is a beautiful refinement in the organisation of the hymenium : it is 

 correlated with the crowding together of the dimorphic basidia and 

 serves to prevent the spores of the short basidia colliding with, and 

 adhering to, the spores of the long basidia during their discharge. 



Owing to the zone-wise discharge of the spores on the two sides of 

 each gill, a spore-deposit of Coprinus sterquilinus made on white paper 

 in the course of a few minutes consists of a series of double black radial 

 lines, each pair of lines corresponding to a single gill. The Aequi- 

 hymeniiferae never produce spore-deposits of this kind. 



Before a spore is shot away from its sterigma a drop of water always 

 appears at the spore-hilum. Sometimes the drops on the four spores of 

 a single basidium become abnormally large, touch one another, and fuse 

 together, in which case the spores are not discharged but eventually 

 come to lie in the zone of the products of autodigestion at the very edge 

 of the gill. 



In conclusion, the author discusses the probable steps in the evolu- 

 tion of the Inaequi-hymeniiferae from the Aequi-hymeniiferae. The 

 numerous irregular waves of hymenial development which one can 

 observe in the mottled gills of many Aequi-hymeniiferae, e.g. Panaeolus 

 campanulatus, may have become altered in their movements so as to 

 form one grand upward-moving hymenial wave such as we now find in 

 the gill of a Coprinus. With the discharge of the spores and the exhaus- 

 tion of the hymenium from below upwards on each gill there becomes 

 associated the progressive death of the gills from below upwards followed 

 by progressive autodigestion of the gills from below upwards. 



Chapter IX. — In the Atramentarius Sub-type : (1) the gills are 

 parallel-sided ; (2) cystidia are present in large numbers on the faces 



