DEVELOPMENT OF THE MUSHROOM. 



13 



sessile, that is, the shelving forms where the pileus is itself attached 

 to the trunk, or other object of support on which it grows. 



Where there is such uniformity in the position of a member or 

 part of a plant under a variety of conditions, it is an indication that 

 there is some underlying cause, and also, what is more important, 

 that this position serves some useful purpose in the life and well 

 being of the plant. We may cut the stem of a mushroom, say of 

 the Agaricus campestris, close to the cap, and place the latter, gills 

 downward, on a piece of white paper. It should now be covered 

 securely with a small bell jar, or other vessel, so that no currents of 

 air can get underneath. 

 In the course of a few 

 hours myriads of the 

 brown spores will have 

 fallen from the surface 

 of the gills, where 

 they are borne. They 

 will pile up in long 

 lines along on either 

 side of all the gills and 

 so give us an impres- 

 sion, or spore print, 

 of the arrangement of 

 the gills on the under 

 side of the cap as 

 shown in Fig. 12. A 

 white spore print from 

 the smooth lepiota 

 (L. naucina) is shown 

 in Fig. 13. This hori- 

 zontal position of the 

 cap then favors the 

 falling of the spores, 



so that currents of air can scatter them and aid in the distribution of 

 the fungus. 



But some may enquire how we know that there is any design in 

 the horizontal position of the cap, and that there is some cause which 

 brings about this uniformity of position with such entire harmony 

 among such dissimilar forms. When a mushroom with a compara- 

 tively long stem, not quite fully matured or expanded, is pulled and 

 laid on its side, or held in a horizontal position for a time, the upper 

 part of the stem where growth is still taking place will curve upward 



Figure 13. Lepiota naucina. Spore print. (Natural size.) 



