INTRODUCTION. 



THE successful pursuit of pathology the science which treats of 

 disease depends largely upon the clearness and accuracy of the stu- 

 dent's knowledge of normal anatomy and normal physiology. 



Leaving aside as not indispensable, and at present not attainable, an 

 accurate definition of life, it is important constantly to realize that the 

 normal living body is a complex and delicate mechanism incapable of 

 creating new forces but able, by means of its cellular and molecular or- 

 ganization, to accumulate or store energy derived from without, releas- 

 ing this under fixed and definite conditions. This storing of energy is 

 possible by means of the capacity of living body-cells to build up com- 

 plex molecular combinations. These, owing to their instability, may be 

 readily resolved into less complex and more stable combinations with 

 the release of the stored-up energy. This it is which makes possible all 

 expression of life. 



Many of the earlier views concerning life and death and health and 

 disease, which have long since given way to more accurate conceptions, 

 still hold a certain sway among the thoughtless, perpetuated by tradi- 

 tional forms of speech. One of these is that disease is an entity, some- 

 thing foreign to the body which may enter from without, and with which 

 the body may struggle and fight, which it may conquer or to whose rav- 

 ages it may succumb. It will be wise for the student constantly to re- 

 member that disease is not a thing, but a process. It is an abnormal 

 performance of certain of the functions of the body. This may or may 

 not be associated with appreciable morphological alterations of the body 

 structure. It is those agencies and conditions to which the body has 

 not adapted itself, which, swaying its normal capacities now one way and 

 now another, induce the functional aberrations and structural alterations 

 by which disease is manifested. 



It follows from this that the functional abnormalities and the struc- 

 tural alterations which make up the signs, symptoms, and lesions of dis- 

 ease involve the expression of no new functional capacities which the 

 normal body does not possess. These may be diminished or exalted, 

 they may be perverted or abolished ; or the cells may now and then re- 

 vert to forms and to phases of activity which the body has long since 

 outgrown or largely suppressed in its slow adaptation to conditions of 

 life which now constitute the normal. But the body in disease manifests 

 no new functions, develops no new forms of energy, reveals no new ca- 

 pacities. 



Thus, if pathology is to be for the student or the practitioner any- 

 thing but a mass of more or less useful facts, he must learn to correlate 

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