DEVELOPMENT OF THE MUSHROOM. 



15 



etc., where the spores readily fall out from the pores of the honey- 

 combed surface or from between the teeth of those sorts with a spiny 

 under surface. If the caps were so arranged that the fruiting surface 

 came to be on the upper side, the larger number of the spores would 

 lodge in the crevices between the extensions of the fruiting surface. 

 Singularly, this position of the fruiting surface does occur in the case 

 of one genus with a few small species. 



Interesting examples of the operation of this law are sometimes 

 met with in abandoned coal mines, or more frequently in the woods. 

 In abandoned mines the mushrooms sometimes grow from the 

 mycelium which spreads out on the rock roof overhead. The rock 



FIGURE 15. Polyporus applanatus. From this view the larger cap is in the 

 normal position in which it grew on the standing tree. Turn one-fourth 

 way round to the right for position of the plant after the tree fell. ( 1/6 

 natural size.) 



roof prevents the plant from growing upright, and in growing later- 

 ally the weight of the plant together with the slight hold it can obtain 

 on the solid rock causes it to hang downward. The end of the stem 

 then curves upward so that the pileus is brought in a horizontal po- 

 sition. I have seen this in the case of Coprinus micaceus several times. 

 In the woods, especially in the case of the perennial shelving 

 fungi, interesting cases are met with. Figure 15 illustrates one of 

 these peculiar forms of Polyporus (Pomes) applanatus. This is the 

 species so often collected as a " curio," and on account of its very 

 white under surface is much used for etching various figures. In the 

 figure the larger cap which is horizontal represents the position of 

 the plant when on the standing maple trunk. When the tree fell 



