INTRODUCTION 



BECAUSE this book is a pioneer in its field, 

 and because many popular misconceptions 

 exist as to the nature of that field, and its relation 

 to others, it may be well to state at the very be- 

 ginning what the subject-matter is, of which the 

 book treats. This is not a book on forestry, be- 

 cause forestry deals only with large tracts of wood- 

 land, the reproduction of forests, and the harvest- 

 ing and marketing of timber. Men who con- 

 cern themselves with the welfare of individual 

 trees in towns and cities ought not to call them- 

 selves foresters — they are, or ought to be, ar- 

 boriculturists. This book deals with one division 

 of the scie;ice of arboriculture. It has nothing, 

 or but little, to say concerning the planting, fertil- 

 ization, pruning, or spraying of trees, all of which 

 are Important parts of the arboriculturist's work. 

 It is devoted entirely to the prevention and repair 

 of physical Injuries to the framework of the tree, 

 such Injuries as are caused by wind and ice-storm, 

 the ignorance or carelessness of men, the attacks 

 of boring insects, and of that silent destroying 

 host, the rot-producing fungi. 



In a general way the field that It covers Is the 



