Spore Surface of a Polyporus 
Here is a very ordinary - looking specimen 
growing beside the stone steps at our back door 
perhaps. Its top is gray; its gills beneath are fawn- 
color. We may shake it as rudely as we will, and 
yet we shall get no response such as the puff-ball 
will give us. But let us lay it upon a piece of 
white paper, gills downward, on the mantel, and 
cover it with a tumbler or finger-bowl, so as to ab- 
solutely exclude the least admission of air. At 
the expiration of five minutes, perhaps, we may 
detect a filmy, pinkish-yellow tint on the paper, 
following beneath the upraised border of the cap, 
like a shadow faintly lined with white. In a 
Spore Surface of a Polygaric 
