AGARICUS. 103 



curving outwards at their ends towards the free 

 surface. * 



b. The sub-hymenial layer, composed of shorter, 

 closely packed cells, constituting a pseudo-parenchyma : 

 it may, however, be recognised, and especially in 

 sections of ' young mushrooms, that this pseudo- 

 parenchyma consists of the short-celled, terminal 

 parts of the hyphal filaments which compose the 

 trama. 



c. The hymenial layer, consisting of oblong, closely 

 packed cells, having their longer axes perpendicular to 

 the outer surface : of these cells two types are to be 

 distinguished 



i. The paraphyses, which are somewhat nar- 

 rower and have smooth rounded ends. 

 ii. The basidia, which are more bulky, and 

 longer : each bears on its end two fine 

 processes (sterigmata) ; at the extreme 

 tip of each of these there appears a swell- 

 ing which develops into the mature spore. 

 Note various stages of development of the 

 sterigmata, and spores. 



VIII. Remove a whole gill carefully from a fresh 

 mushroom, mount it on a slide, without any reagent or 

 cover-slip, and examine its surface with a medium 

 power : it may then be seen that the dark colour is 

 due to the dusky spores, which are thickly distributed 

 over the surface of the gill in pairs, two being pro- 

 duced from each basidium : note further the pale 

 colour of the tissue of the hymenium, and the rounded 

 ends of the paraphyses, and of those basidia which are 

 young, or have already produced mature spores. 



