228 PRACTICAL BOTANY 



Lay the pileus of a mature mushroom with its lamellae down- 

 wards 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 configu- 

 ration of the under surface of the pileus, produced by the fall 

 of the minute, dark-coloured spores. 



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 i to "5 per cent, chromic acid ; wash with water, and 

 then successively with 50, 70, and 90 per cent, methylated 

 spirit : the tissues will assume a cartilaginous character, 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 of 

 the stipe so as to include both peripheral and central tissues : 

 mount in glycerine, and examine first with a low power : ob- 

 serve 



1. The whole is a spurious tissue, composed of elongated 

 septate tubes (hyphse), which are closely interwoven. 



2. The diameter of the individual hyphas is less, and they 

 are more closely packed towards the periphery than near the 

 centre of the section. 



Examining the sections under a high power it will further be 

 observed 



1. That the hyphae are branched, while occasionally their 

 endings are to be seen. 



2. That they are thin-walled, the transverse or oblique septa 

 being so disposed that the cells are not much longer than 

 broad. 



3. The protoplasmic contents of the hyphae which make up 

 the bulk of the tissue are far from being copious, while no 

 single, well-marked nucleus is to be found in the individual cells. 



VI. Cut transverse sections of the stipe, and, treating as 

 before, observe that the hyphas appear circular in section, that 

 they are more loosely packed towards the centre than at the 



