HYMENOMYCETES 347 



The one observable line of evolution is in the direction of 

 gaining a greater spore-bearing surface or hymenium by the 

 rearrangement of an equal amount of material. This idea 

 is illustrated by comparing Clavaria pistillaris with C. 

 formosa. The former has a solid, undivided, typically 



FlG. 10 r. C lav aria fastigiata. A saprophytic fungus 

 growing on the ground among grass, and obtaining its 

 food from humus. Nat. size. 



club-shaped, erect sporophore, ten to fifteen cm. high, and 

 two to three cm. diameter at the thickest part. The entire 

 surface of the sporophore is covered with the hymenium. 

 In C. formosa^ the gross weight of which does not exceed 

 that of C. pistillaris^ from a stout, very short, solid base 

 spring numerous slender, closely compacted branches and 

 branchlets, each completely covered with the hymenium, 



