THE PREVALENCE OF FOMES ANNOSUS. II3 



necessary to cause infection, it will be seen that in open 

 porous soils, a slight movement on the part of the fungus 

 secures a new victim. From all accounts, the hyphae are 

 able to move for short distances through open soil. Such is 

 not the case in impermeable soils where the fungus may be 

 tied down to one tree and is then forced to produce spores. 

 The importance of this fact is obvious. The fungus may exist 

 for years and be overlooked in a plantation, doing considerable 

 damage underground, without the need for producing the white 

 sporophores. This may also account for the fact that there 

 is still an unwillingness to connect heart-rot and root-rot with 

 Fames annosus. 



Like most other fungi. Fames annasus must originally have 

 fulfilled some definite task in the scheme of things. From the 

 method of its attack, it appears to have at first confined itself 

 to dead material, such as old roots, stumps, fallen stems and 

 branches. It may also have attacked old trees, gaining an 

 entrance through a decayed root or wound and living upon 

 the dead tissue of the wood inside the stems and roots. It 

 seems, in fact, to have been originally purely saprophytic, 

 confining itself entirely to lifeless material. If trees were still 

 grown on ground suited to their requirements, such a state of 

 affairs would doubtless continue to exist and, indeed, assuming 

 that the woods were carefully cleared of dead materials and all 

 stumps extracted, the fungus would soon become of very rare 

 occurrence. Such, however, is not by any means the case. 

 So many new species of trees have been introduced and planted 

 indiscriminately here, there, and everywhere, without the 

 slightest consideration as to their soil requirements ; so great 

 has been the demand for rapid-growing conifers to replace the 

 slower hardwoods ; that, of necessity, a great number of woods 

 have been planted in altogether unsuitable conditions, with the 

 result that trees have grown weakly and enfeebled and become 

 an easy prey to fungi and other pests. These fungi, naturally 

 saprophytic, have gained a footing in the weakened or dead 

 tissue of even young trees, and have ultimately become more 

 or less parasitic in habit. Trees will not be attacked by 

 Fames annosus unless they have first been rendered easy of 

 attack, owing to damage of some kind to the roots underground. 

 When we can discover what agency it is in the soil which first 

 attacks the roots and so renders them open to further damage 



VOL. XXXV. PART II, H 



