DEVELOPMENT OF THE MUSHROOM. 



9 



tion shows, of mycelium threads. The center of the gill is called 

 the trama. The trama in the case of this plant is made up of threads 

 with rather long cells. Toward the outside of the trama the cells 

 branch into short cells, which make a thin layer. This forms the 

 subhymenium . The subhymenium in turn gives rise to long club- 

 shaped cells which 

 stand parallel to each 

 other at right angles 

 to the surface of the 

 gill. The entire sur- 

 face of the gill is 

 covered with these 

 club-shaped cells 

 called basidia (sing. 

 basidintn). Each of 

 these cl ub-shaped 

 cells bears either two 

 or four spinous pro- 

 cesses called sterigmata 

 (sing, sterigma), and 

 these in turn each bear 

 a spore. All these 

 points are well shown 

 in Fig. 8. The basidia 

 together make up the 

 hymenium . 



Wood Destroying 

 Fungi. Many of the 

 mushrooms, and their 

 kind, grow on wood. 

 A visit to the damp 

 forest during the sum- 

 mer months, or during 

 the autumn, will reveal large numbers of these plants growing 

 on logs, stumps, from buried roots or rotten wood, on standing 

 dead trunks, or even on living trees. In the latter case the 

 mushroom usually grows from some knothole or wound in the 

 tree (Fig. 9). Many of the forms which appear on the trunks of 

 dead or living trees are plants of tough or woody consistency. They 

 are known as shelving or bracket fungi, or popularly as " fungoids 5I 

 or "fungos." Both these latter words are very unfortunate and 

 inappropriate. Many of these shelving or bracket fungi are perennial 



FIGURE 9. Polyporus borealis, showing wound at base of 

 hemlock spruce caused by falling tree. Bracket fruit 

 form of Polyporus borealis growing from wound, (i 15 

 natural size.) 



