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PREFACE. 



IN presenting to the student of medicine so condensed a volume 

 upon normal and morbid histology an explanation of the author's 

 purpose may, perhaps, not be amiss. 



It appears to the writer that the most important lesson to be 

 derived from a study of the tissues in health and in disease is 

 a knowledge of the constant and potent activities of the cells to 

 which those tissues owe both their origin and usefulness. When 

 the body develops under normal conditions those cells build up the 

 tissues, gradually modifying their formative activities so as to oc- 

 casion a diversity of structure in the various parts of the body. 

 During this developmental epoch, and after maturity is attained, 

 the activities which are grouped as functional, and which it is the 

 lot of the tissues to maintain, are also carried on by the cells. 



But in order that these manifold cellular activities shall be of the 

 usual or " normal " character, the conditions under which they are 

 carried on must not depart greatly or for any considerable length 

 of time from a certain usual, but rather indefinite standard. If 

 those conditions are materially altered, the cellular activities become 

 modified, and the functions they perform suffer aberration, as a 

 result of which structural changes in the cells and tissues may 

 ensue. 



It is this close relation between cellular activity and structure 

 which unifies the subjects usually kept distinct under the titles of 

 normal and pathological histology, for it is evident that there is no 

 natural separation between those subjects. 



In the preparation of this manual the author has steadfastly kept 

 in view such a conception of the relations between cellular activity 

 and structure. To carry out this purpose it did not appear neces- 

 sary to describe the various changes wrought in the individual 

 organs or tissues by unusual conditions. It seemed to him that a 

 general statement of the alterations in structure attributable to 



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