EVOLUTION OF THE COPRINI 257 



Fig. 104 (p. 242) would be enveloped in this way if the zone were to 

 rise 0-15 mm. As spore-discharge proceeds, the number of spores 

 accumulating at the gill-edge gradually increases until so many are 

 collected that they become visible to the naked eye as a thin black 

 line. Many of these waste spores have a perfectly normal appear- 

 ance, but others a distinctly abnormal one. Some of the latter 

 (c/. Figs. 104 and 105, pp. 242 and 249) are undersized, some over- 

 grown, and some partially pigmented or even colourless. As we 

 have seen, the number of spores produced on a pileus may be as 

 many as 100,000,000. It should therefore be no matter for surprise 

 when we find that of this huge total some tens or even hundreds of 

 thousands of spores may be wasted. However, the number of waste 

 spores along the gill-edges of an exhausted pileus is probably less 

 than 5 per cent, of the total number produced ; and certainly it is 

 always small relatively to the number of the spores liberated into 

 the air. In accumulating waste spores upon its gills, Coprinus 

 sterquilimis does not differ from other Inaequi-hymeniiferae or 

 from such Aequi-hymeniiferae as Panaeolus campanulatus, Stropliaria 

 semiglobata, and Psalliota campestris. My experience goes to show 

 that none of the Hymenomycetes are so perfectly organised that all 

 the spores developed are properly discharged. Several scores of 

 species have come under my observation, but in all of them some 

 waste spores were found upon the hymenium. 



Conclusion and Discussion of the Probable Steps in the Evolution 

 of the Inaequi-hymeniiferae. — As already stated in Chapter VI, ^ I 

 have come to the following highly important theoretical conclusion : 

 m the genus Coprinus, the ripening and discharge of the spores fro?n 

 below upwards on each gill, and the autodigestion from below upwards 

 on each gill, are special arrangeynents ivhich permit of successful 

 spore-discharge froin parallel-sided {and sub parallel-sided) ageotropic 

 gills. This conclusion fits all the facts that have been brought 

 forward in this ChajDter in resj^ect to the production and liberation 

 of spores in Coprinus sterquilinus ; for, in this species, it is clear 

 that, owing to the fact that the zone of autodigestion follows hard 

 after the zone of spore-discharge, constantly destroying the spore- 

 free zone from below upwards, the obstacle to the fall of the spores 



1 Chap, vi, p. 119. 



VOL. III. 



