C.ENKRAL INTRODUCTION li 



from external dangers, but considerable evolution is evident in the 

 way of producing a greater spore-bearing surface from an ec^ual 

 amount of material. In Clavaria pislillaris (Plate XXXIV, Fig. 0) 

 we have a large, fleshy, club-shaped fungus, the even surface of 

 which bears spores everywhere. Now if we examine Clavaria 

 cinerea (Plate XXXIV, Fig. 5), we at once realize that it contains 

 actually less material or weight of substance than C. pistillaris, 

 but as the substance is broken up into numerous branches, each 

 entirely spore-bearing throughout its surface, we grasp the fact that 

 C. cinerea, by becoming broken up into numerous branches, can 

 produce more spores than the heavier C. pistillaris. Clavaria aurea 

 (Plate XXXIV, Fig. 8) illustrates to what extent brandling, for 

 the purpose of increasing the spore-bearing surface, is carried in the 

 family. Notwithstanding the great advance made by the members 

 of the Clavariaceas in the increase of the hymenium or spore- 

 producing surface, by gradually breaking up a solid mass of tissue 

 into a much-branched, tree-like structure, the idea was not per- 

 petuated in succeeding families, due probably to the entire absence 

 of protection to the hymenium, all the species growing upright, and 

 having the hymenium exposed from first to last. 



In tlie Hydnaceffi we observe a marked advance, both in securing 

 a greater spore-bearing area, and in protecting the same. In the 

 simpler genera, as Grandinia, the hymenial surface is densely 

 covered with minute warts, which collectively expose a much 

 greater area than the perfectly smooth surface in Corticium. The 

 line of development followed is the gradual conversion of warts 

 into densely crowded, elongated spines, as seen in Hydnum re- 

 pandum (Plate XX\TI, Fig. 7). From the protective standpoint, 

 the fungi included in this family evolve by transitions from the 

 crust-like expansions of Corticitim, through the partly free portion 

 as described in Stereum, to a symmetrical, umbrella-shaped structure 

 with a central stem, and having the hymenium composed of spines 

 arranged on the under surface of the cap, and thus protected against 

 rain, dust, etc., as in Hydnum repandum. The conception of in- 

 creasing the spore-bearing area, by covering the surface of densely 

 crowded spines with the hymenium, dropped out with the Hyd- 

 naccce ; and in the next family, the Polyporaceae, we meet with 

 numerous pits of various degrees of depth crowded on the spore- 

 bearing surface, the walls of the depressions being covered with the 

 hymenium. In some genera, as Merulius and Polystictus (Plate 

 XXXI, Fig. 4), the pits or pores are quite shallow, whereas in the 

 higher species, as Boletus (Plate XXXVII, Figs, i, 3, and 4), the 

 pores are up to half an inch deep, or sometimes more, the wall of 

 the entire inner surface of each pore bearing spores. The sequence 

 of progression of tlie fungus ranges from a plate-like crust, as in 

 Poria (Plate XXXI, Fig. 3), through horizontal forms, as in 

 Polystictus (Plate XXXI, Fig. 4), to species with a convex cap, 



