456 PRACTICAL BOTANY 



surface, and note the radiating, more or less darkly 

 coloured lamellae,, some of which extend the whole 

 way from the margin to the insertion of the stipe, 

 others only a part of that distance. 



Lay the pileus of a mature mushroom with its lamellae 

 downwards on a sheet of white paper for a few hours : 

 on removing it there will be seen on the paper a sort of 

 print of the configuration of the under surface of the 

 pileus, produced by the fall of the minute, dark-coloured 

 spores : the white lines of the print correspond to the 

 spaces between the lamellae. 



This may be particularly well seen in the small Coprinus, 

 which appears with great constancy on horse-dung after it 

 has been kept at a moderate temperature under a bell-glass 

 for three or four weeks. This fungus shows on a small scale a 

 structure similar to Agaricus, and will serve well as a second 

 type, and it is especially useful since it can be obtained at any 

 time of year. 



V. In order to study the structure of the mushroom 

 by means of sections, it is a great advantage to harden 

 the material, and the following treatment has been 

 found to produce good results : treat the fresh material 

 for about twenty-four hours with 1 to *5 per cent, 

 chromic acid ; wash with water, and then succes- 

 sively with 50, 70, and 90 per cent, methylated 

 spirit : the tissues will assume a cartilaginous charac- 

 ter, which makes it possible to cut fine sections : in 

 preparing large specimens it is an advantage to cut 

 them up into pieces of moderate size, so that the 

 reagents may gain more ready access to the internal 

 parts. 



From material thus treated cut longitudinal sections 



