AGARICALES 463 



triangular cross section below, e.g., grow narrow toward the edge and 

 leave open a widening space for the spores to fall through, in the Copri- 

 naceae the walls are parallel and the space for discharge and fall is just 

 as narrow at the distal end as at the proximal. Further, the lengthwise 

 axis of the lamellae in mature fructifications does not lie parallel to the 

 ground, as in many other Agaricales, but is more or less perpendicular to 

 it. Since this axis runs in the direction of fall, a spore under some 

 conditions would fall several centimeters along its surfaces. There is 

 danger that the spores in question may hit the cystidia or the lamellae 

 and thus fail to reach their destination to allow dispersal by wind. By 

 this differential maturing of the spores and the immediate subsequent 

 autolysis of the exhausted tissue, there is an elimination of those parts of 

 the lamellae which have already fulfilled their function and whose longer 

 presence would hinder the fall of the remaining spores. The cystidia 

 are autolysed somewhat earlier (often less than a half hour) than the 

 remaining tissue. The fact that in those species in which the lamellae 

 spread at the expansion of the pileus, e.g., in C. niveus, autolysis is weak 

 and limited to the edge of the pileus, also points to the correctness of 

 this interpretation of autolysis. 



The basidiospores are thick walled and provided with a terminal 

 germ pore. Their germination was discussed in detail on page 397. 

 In some species, as C. ephemerus and C. lagopus, there occasionally 

 arise on the primary mycelia small fascicles of short side branches which, 

 as in numerous other Basidiomycetes, break up into bacilliform oidia. 

 Generally these oidia are formed in such large masses that they obscure 

 the cultural characters (Brefeld, 1877). In some species, as C. ster- 

 corarius, the hyphae later intertwine to dark-coated sclerotia up to the 

 size of hazel nuts which, under certain conditions, develop to 

 fructifications. 



The Coprinaceae may be divided into two genera, Coprinus (spores 

 black or brownish black) and Bolbitius (spore ochraceous, yellow under 

 the microscope). The majority of these two genera are found on dung. 

 Many are palatable when young, as Coprinus comatus, the shaggy 

 mane. 



Paxillaceae. — In this family the lamellae are easily separable from 

 the pileus; as, however, this character appears occasionally in other 

 families, especially the Clitocybeae, its consideration as a separate family 

 is open to question. Its significance lies in the fact that in many species 

 the lamellae, particularly at the fundament of the stipe, anastomose like 

 veins and finally fuse to Polyporaceous tubiform networks (e.g., Paxillus 

 rhodoxanthus) . This peculiarity forms the point for the connection of 

 the Boletaceae which are always tubiform and hence generally placed 

 beside or in the Polyporaceae, although their ontogenetic characters 

 suggest the Agaricales. 



