WHAT IS A DISEASE? 231 



bystanders only ; or, like a cardiac murmur, or fluctuation, or 

 optic neuritis, it may not be perceptible except to the skilled 

 examination of the physician ; or it may, like cough, vomiting, 

 swelling, and other deformity, be perceptible both to the patient 

 himself and to others. It may be, like a barking cough or 

 an elephantic leg, gross as a mountain, open, palpable ; or it 

 may be, like want of sensitiveness in a pupil, or diminution of 

 a knee-jerk, so slight that we can scarcely be sure that it is 

 present. It may, like a cavity in a tooth or a phlyctenule on 

 the eye, show unmistakably what function of what part is 

 disordered ; or it may, like headache, give no indication 

 whatever ; but in every case in which function is disordered, 

 some sign or manifestation of the disorder is perceptible to 

 some one ; and such a sign or manifestation is called a 

 symptom. This, then, is the definition of a symptom. It is 

 a sign or manifestation of disorder of the function, intrinsic 

 or extrinsic, of some part of the body. 



Disease is a wide and comprehensive term, covering not 

 only all disorders of function, and all symptoms, or signs of 

 disordered function, but also all results of disorder of function, 

 whether the function disordered is intrinsic or extrinsic. Thus, 

 indigestion, which is disorder purely of extrinsic function, is 

 disease : atrophy, which is disorder purely of intrinsic function, 

 is disease : albuminuria, which is a result of disorder of ex- 

 trinsic function, is disease : a lardaceous liver or a cancerous 

 breast, which is a result of disorder of intrinsic function, is 

 disease : pain, which may be a manifestation of disorder of 

 either intrinsic or extrinsic function, is disease. 



So far all is plain sailing, and I do not think any one will 

 object to anything that has been said ; but when we modify 

 the term by the addition of the article, and speak of ' a 

 disease ' we are at once entangled in a thicket of difficulties. 

 Pain is disease ; but it is not,- at least it is not necessarily, a 

 disease. Albuminuria is disease ; but it is not a disease. 

 Hsematemesis is disease ; but it is not a disease, at least it is 

 not now so considered, though there was a time when not only 

 haematemesis, but cough, hematuria, albuminuria, vomiting, 

 dropsy, palsy, jaundice, syncope, and many other instances of 

 disease that are now ranked as symptoms only, were ranked 

 as diseases. 



From this we gather, first that not everything that is 



