X-2 



cn yp TouA MO us t ypes. 



A, Fig. 314, ami if we magnify one of these cross-sections it 

 will api^ear as at B, where there is seen an outer laj'er of 

 cells standing on end. The wliole of both surfaces of the 

 lamellffi is covered with such cells, and this special layer 

 is the hiimcnlum. At C, the left-hand portion of the 

 figure shows a- number of these cells much more highly 

 magnified, some of them narrowed in at the top so as to 

 form slender points, upon each of wliich is a rounded 

 body. Tliese rounded bodies are the spores ; the narrowed 

 ends of the cells are called sterifjmata^ and the projecting 

 cells wliich bear them are specially known as hasidia. 

 The spores are formed by the simple narrowing in of the 

 outer ends of the basidia. 



The mycelium is, therefore, the vegetative part of the Mush- 

 room while the stalked pileus above the surface is the 

 fructification. The mjxelium is developed directly from 

 the spore, but so far there have not been discovered any 

 indications of the interaction of sperm-cells and germ-cells 

 such as characterize the Bryophytes and Pteridophj^tes. 



You will note the entire absence of green colouring-matter. 

 The Mushrooms produce no chlorophyll, and, conse- 

 quentlj', are incapable of assimilation. They are always 

 found growing upon decaying organic matter, as the leaf- 

 soil of forests and meadows, etc. 



The Mushrooms are representatives of a large class of plants 

 called Fungi, all the members of which are destitute of 

 chloroplij'll. The cells of which they are made up are 

 generally' in rows so as to form long threads which are 

 known as hypJxe, and these may be either loosely inter- 

 woven, as in ordinary Moulds, or firmly compacted to- 

 gether, as in the Mushroom. 



As just mentioned. Mushrooms are saprophytic in their habits; 

 but there are also Fungi w^hich are parasitic, such as Rust 

 and Smut. To the Fungi belong such organisms as the 

 Yeast-plant, and the Bacteria which are found in putre- 

 fying matter, and are the cause of, or are associated with, 

 diseases of various kinds. 



Lichens. 



Tliese plants may be found growing on the bark of trees, on 

 old fences, on rocks, or on the ground. They differ widely 

 in external appearance, sometimes growing erect and imi- 

 tating a stem and branches, as in Fig. 315 ; sometimes 

 forming flat expansions which adhere to the surface upon 

 which they grow, as in Fig« 316. Some species are yel- 

 low, others red, others grey. A very common one is that 

 represented in Fig. 316. It may be found on many tree 

 trunks, and will be easily recognized by the yellow disks 

 which dot its surface. 



Fig. 313. 



