COPRINUS COMATUS 155 



then recognised the short practically non-protuberant basidia as 

 regular elements of the hymenium. It is now clear, however, that 

 the protuberancy of the long basidia is directly correlated with the 

 lateral crowding of the basidia taken as a whole, and that it is there- 

 fore correlated with an increase in the number of spores produced on 

 the fruit-body. 



To sum up the above discussion as it affects Coprinus comatus, 

 we may state that the dimorphism of the basidia, associated with 

 lateral crowding, is a beautiful refinement in organisation which, 

 by increasing the number of spores developed on each unit area of 

 the hymenium, makes an important contribution to the efficiency 

 with which the fruit-body cames out its one dominant function of 

 producing and liberating spores. 



The area of the hymenium shown in Fig. 60, A and B (p. 153), 

 contains 91 spores belonging to the short basidia and 76 belonging to 

 the long basidia, which indicates that the short basidia on this area 

 numbered 22-75 and the long basidia 19. A similar inequality 

 between the two sets of basidia was found to occur on other areas. 

 The general rule, therefore, is that on any given area of the hymenhnn 

 the short basidia slightly outnumber the long basidia. It may be that 

 this rule is correlated with the relative difficulty of setting the basidia 

 in definitely safe positions so far as the possible jostling of their 

 spores is concerned. Two adjacent short basidia, since their bodies 

 do not protrude beyond the general level of the exterior of the 

 paraphyses, cannot incline appreciably toward one another, whereas 

 two adjacent long basidia, owing to their considerable protuberancy, 

 may not be perfectly perpendicular and may therefore incline 

 toward one another at a greater or less angle. Perhaps, therefore, 

 the more liberal spacing of the long basidia, relatively to the short 

 basidia, is correlated simply with the fact that the longer basidia. 

 relatively to the shorter, require a larger margin of safety to prevent 

 jostling of their spores. 



The elements entering into the structure of the hymenium on the 

 sides of the gills are simply the two generations of basidia already 

 described and the paraphyses. Cystidia are not present. The 

 mosaic-work formed by the basidia and paraphyses is well shown 

 in Fig. 61 at A which consists of a plan of a piece of the hymenium 



