AGAIUCUS 459 



2. The sections through the lamellae show a differ- 

 entiation into 



a. The central portion (trama), in which the sep- 

 tate hyphal filaments are easily recognized running 

 longitudinally down the middle of each lamella, and 

 curving outwards at their ends towards the free 

 surface. 



&. The sub-hymen ial layer, composed of shorter, 

 closely-packed cells, constituting a pseudo-parenchyma : 

 it may, however, be recognized, 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- 



