248 



Bulletin 193. 



centric ridges and furrows. The marginal ridge is the one repre- 

 senting the Litest year's growth. The cohjr of the fruit body is 

 from dark l)rown to nearly black at the base, varying to a reddish 

 brown near the margin. The marginal zone representing the latest 

 irrowth varies in color accordinir to the time of collection. AVhen 

 the marginal zone is youno- it is whitish or yellowish in color, 

 becoming reddish yellow or red later in the season and having 

 then a shining polished surface. The under surface is yellowish 

 white, and on bruising, the yellow color is often more distinct. 

 The pores of the under surface are just visible to the naked eye. 

 ()!i sectioning the fruit l)ody the annual layers seem quite distinct. 



83. — Section of fruit J>ody of Polyiiorus applanatiis, showing tiibe strata. 



The size and distinctness of these concentric 'elevations or zones 

 on the up])er surface of the fruit body vary according to the rapidity 

 of growth. Where the growth is rapid the zones are large and 

 prominent on the fruit body, increasing rapidly in size each year. 

 One fine specimen collected on a hemlock spruce in the vicinity of 

 Ithaca is 40 cm. broad by 25 cm. long, and is only six or eight years 

 old, there being apparently two imperfect zones which may repre- 

 sent years of very slow and imperfect growth. Of the six annual 



