364 DISEASES OF CULTIVATED PLANTS 



The foregoing suggests the great probability that all the 

 species enumerated are capable of acting as parasites, and of 

 doing a great amount of injury, yet in no instance has this 

 surmise been corroborated by scientific research. This 

 awaits some one with time and facilities at command. 



POLYPORACEAE 



The most characteristic structural feature of the present 

 family consists in the hymenium or spore-bearing surface 

 being composed of tubes, the cavities of which are lined 

 with basidia bearing the spores. In a typical genus like 

 Polyporus these tubes are elongated, sometimes exceeding 

 half an inch in length, and arranged closely side by side, 

 resembling a number of closely packed drain-pipes standing 

 on end. As would be expected, all genera are not equally 

 typical, and in some instances the pores are quite shallow, 

 and in others, as Merultus, the entire surface of the hymenium 

 is covered with slightly raised anastomosing veins, which 

 form shallow pits or depressions on the surface. 



On the other hand such genera as Dacdalea, which form a 

 connecting-link between the Polyporaceae and Agaricaceae, 

 show a decided tendency to form gill-like structures on the 

 hymenium, in fact it is not unusual to meet with both gills 

 and pores on different parts of the hymenium in Daedalea. 



Many of the largest of fungi belong to the present family, 

 as also some of the most durable, the perennial species of 

 Fomes often being of a woody consistency. All the large 

 bracket-shaped or hoof-shaped fungi, so common on trunks, 

 are members of the present family. 



The species are pre-eminently wound-parasites, although 

 some few are true parasites. The majority attack trees,, 

 causing various kinds of wood decomposition, as heart-rot, 

 root-rot, etc. 



Many species, the properties of which have not been 

 investigated, grow on living trunks, and will probably be 

 shown to be parasites. 



MERULIUS (HALL) 



Hymenophore resupinate, subgelatinous, surface variously 

 plicate, surrounded by white, radiating mycelium. 



Distinguished by the subgelatinous consistency when moist. 



