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tree, but its value for timber has been destroyed. Besides the insects 

 and fungi, diseases which may be characterized as physiological are 

 not unconmion. They may be due to an insuificient supply of light, 

 heat, water, or food, etc. Often insects and fungi act in conjunction 

 with other unfavorable agencies, and it then becomes a matter of con- 

 siderable difficulty to ascertain the true cause of the disease. The 

 present paper deals onl}^ with diseases due to fungi. 



The mycelia of fungi attack living trees as well as dead ones. When 

 on living trees they grow either in the living parts, the roots, leaves, 

 bark, or newer wood cells, or in the dead parts, the heartwood of the 

 roots, trunk, and branches. The character of the injury which the 

 mycelium causes depends much upon its place of growth, whether on 

 the leaves or within the wood. Injury to the leaves may often be very 

 great, as is the case with fungi like the Erysiphece^ TJredinecB^ Exoas- 

 cece, and others. The injury caused by those which grow in the living 

 bark or cambium, like the species of NectHa^ for instance, is very large. 

 A large class of fungi flourishes within the heartwood of trees, 

 growing into it through a branch or some wound, and in some cases 

 through the roots. The effect of their growth is to destroy the heart- 

 wood, iilling it with holes or turning it to a brittle substance which has 

 none of the properties of ordinary wood. These changes weaken the 

 trunk, and at some period or other the tree is broken by the wind. 

 T lose forms which enter through the roots may kill the latter first, and 

 t'lus cause a tree to fall. The wood is then rapidly destroyed by a large 

 variety of fungi and insects. It is therefore to the interest of the for- 

 ester who grows trees for their wood to determine what fungi so 

 affect the trees as to render the wood unfit for lumbering purposes. 



In Europe, where forests have been grown for many years, the 

 importance of understanding the diseases of forest trees has long been 

 recognized, as is well shown by the works of Hartig, Tubeuf , Marshall 

 Ward, Frank. Nypels, and others. These show that it is possible to 

 prevent the growth of many of these fungi by destroying their fruiting 

 bodies, and, in general, by bringing about conditions unfavorable to 

 their growth and development. In order that this may be properly 

 and successfully done, it is first necessary to know what the destructive 

 fungi are and where and how they live. It was with this end in view 

 that the writer spent several months during the year 1899 in the for- 

 ests of Maine. A preliminary survey was made of the forests of that 

 State, and the results are here presented in preliminary form. 



WHERE THE IXVESTIGATIONS REPORTED AVERE MADE. 



The region about Houlton in Aroostook County was first visited, 

 then the territory north of Moosehead Lake, and during September 

 the region about the Rangeley Lakes. A large part of the summer was 

 spent on the coast at Linekin (near Boothbay Harbor, Maine), where 



