ROT-FUNGI AND THEIR WORK 73 



of which is now checked and weathered and moist. 

 Here all the conditions are favorable, and in a 

 few days the spore begins to grow and sends out 

 a minute root-like organ containing living proto- 

 plasm. This hypha grows and branches and soon 

 makes up quite a mass of fibers, gradually working 

 its way into the heart of the tree. The hyphae, 

 considered together, are called the mycelium of 

 the fungus, and really constitute the fungus plant. 

 The brackets and mushrooms which appear on the 

 outside of the trunk are special bodies in a way, 

 fruits developed by the plant solely for the pro- 

 duction of spores, and called, on that account, 

 sporophores. The living tips of the hyphae make 

 their way through the wood in various ways. 

 Some work in between the cells, sending little root- 

 like branches through the walls of the cells to 

 suck out what is nourishing of their contents. In 

 other cases the tips of the hyphae exude ferments 

 which dissolve the cell walls and permit the hyphae 

 to grow freely throughout the wood, consuming 

 part of it and leaving the rest fragile and dis- 

 united. 



Although the hyphae of the fungus are quite in- 

 visible to the naked eye, the result of their work 

 is easily detected. The wood changes in color, 

 texture, and weight. These changes, however, 

 are to a large extent gradual. In the case of some 

 fungi it is very difficult to draw a line in a cross- 



